As dogs get older, their bodies change, and their food may need to change too. But older dogs often have more sensitive stomachs than they did when they were young, so a sudden switch can leave them with diarrhoea, wind or a lost appetite. The good news is that a slow, careful transition avoids most of those problems. This guide covers when your dog becomes a senior, whether they need a senior food, and a step-by-step plan for making the change gently.
When is a dog a senior?
It depends on size. Bigger dogs age faster than small ones. As a guide:
- Small breeds (under 10kg): around 10 to 12 years.
- Medium breeds (10 to 25kg): around 8 to 10 years.
- Large breeds (25 to 45kg): around 6 to 8 years.
- Giant breeds (over 45kg): around 5 to 6 years.
You'll often notice the signs first: a greying muzzle, longer naps, slower walks, stiffness when getting up, or a change in weight.
Does my dog need a senior food?
Not every older dog has to switch straight away. A dog who is a healthy weight, full of energy and doing well on their current food may be fine as they are. A senior food is worth considering if your dog is:
- putting on weight as they slow down
- losing muscle, especially over the back legs and spine
- getting stiff or slower on walks
- having trouble chewing larger kibble
Senior foods usually have fewer calories to match a slower lifestyle, high-quality protein to help maintain muscle, added joint support like glucosamine, antioxidants, and often a smaller or easier-to-chew kibble.
Check in with your vet first
Before changing your older dog's food, it's worth a vet check, ideally with a blood test. Conditions like kidney or liver disease are more common in older dogs, and some need a prescription diet rather than a standard senior food. Weigh your dog before you start, and take note of what their normal stools look like, so you can spot any changes.
A slow 14-day transition plan
Younger dogs can usually switch food over 7 to 10 days. For older dogs, allow about two weeks:
- Days 1–4: one-quarter new food, three-quarters old food.
- Days 5–8: half and half.
- Days 9–12: three-quarters new food.
- Days 13–14: all new food.
If your dog's stools turn soft at any stage, go back to the previous step for two or three days before moving on. There's no prize for finishing quickly.
Tips to keep their tummy settled
- Stay with the same brand if you can. The ingredients and kibble will be similar, which makes the change gentler.
- Change one thing at a time. Don't introduce new treats, chews or supplements during the switch.
- Split the daily amount into two or three smaller meals. Smaller meals are easier for older dogs to digest.
- Soften the kibble with a little warm water for 10 minutes if your dog has sore or missing teeth. Serve it straight away and throw out any leftovers.
- Keep fresh water available, as older dogs can dehydrate more easily.
- Weigh your dog every couple of weeks and adjust the amount. Senior foods are often lower in calories, so follow the new feeding guide rather than using the same scoop.
When to stop and see your vet
Older dogs can go downhill faster than young ones when they're unwell. Pause the switch and call your vet if your dog has:
- vomiting, or diarrhoea lasting more than a day
- blood in their stools
- refused food for more than a day
- low energy, or seems unwell
Senior foods we stock
Hill's Science Diet Adult 7+. Easy to digest, with antioxidants and balanced minerals to support the heart, kidneys and bladder. Also available as 7+ Small Bites and 7+ Small & Mini, and Senior Vitality for dogs who've lost their spark.
Hill's Science Diet Adult 6+ Large Breed. Made for big dogs from 6 years on, with natural sources of glucosamine for joints carrying a large frame.
Addiction MEGA Large Breed Senior. Glucosamine and collagen for joints, and protein to help maintain muscle. An easy next step for dogs already on Addiction MEGA Large Breed Adult.
Eukanuba Senior Medium Breed. Over 50% more glucosamine than Eukanuba Adult Medium Breed, plus chondroitin, DHA and antioxidants for active older dogs. There's also a Senior Large Breed version.
Royal Canin Mini Mature Adult 8+. Made for small dogs from 8 years on, with extra palatability for fussy older eaters. Royal Canin also has Medium Senior 10+, Maxi Mature 5+ and Maxi Senior 8+, plus breed versions for Labradors and German Shepherds.
Mighty Mix Nourish. Mighty Mix's most nutrient-dense biscuit, made for puppies, seniors and recovering dogs. A natural next step for older dogs already on Mighty Mix. Click and collect only.
Hill's, Royal Canin and Eukanuba are ordered in especially for you, so allow a few extra days, and order before you run out of your current food so you have enough for a slow switch. Not sure which suits your dog? Call or pop into our Oxford store and we'll talk it through with you.
Not ready for a senior food yet?
If your dog is still fit and a healthy weight but starting to stiffen up, a joint-support adult food like Black Hawk Healthy Benefits Joints & Muscles can be a good middle step. If weight is creeping up, our guide to why dogs gain weight can help.
Find the right food for your older dog
Browse our full range of dry dog food, with delivery across New Zealand and click and collect from Oxford, North Canterbury. Or get in touch and tell us about your dog. We're happy to help you choose.
This article is general information, not veterinary advice. If your dog is unwell, see your vet.