Feeding an Older Cat or Dog: What the Blood Test Shows

Calling a cat or dog "old" describes a set of changes that have already happened but have not yet reached the surface. The blood test sees them before the owner does. So feeding an older dog is a question that starts with two sheets of paper — a complete blood count and biochemistry — not with a shelf in the pet shop.

What Changes in an Older Cat or Dog

Age itself is not a disease and not a reason for a "gentle" table. What actually changes is this:

• Muscle goes before fat. Muscle loss continues even when the scales look normal. That is why an older cat or dog often needs more protein, not less: protein is spent holding muscle in place.
• Cats over 11–12 digest fat and protein less well. Some senior cats absorb food noticeably worse, and a "light" low-calorie diet makes their weight loss faster.
• Smell, taste and teeth. A pet may refuse food not because of internal disease but because chewing hurts or the food no longer smells of anything.
• Organs age unevenly. One cat has excellent kidneys at 14; another is already at stage two at 9. The birthday does not tell you which is which.

Hence the rule: feeding an older pet is decided by the organ that gave way first, and that is what the blood test shows.

Which Markers Decide the Bowl

How the form itself is read by species is covered in cat blood test and dog blood test. A separate category is therapeutic pet food: not a "premium" label but a diet built around one specific abnormality, prescribed from results rather than from age.

Feeding an Older Dog: Protein, Weight and Joints

For a healthy senior dog the task is simple — keep the muscle, avoid the extra kilos. In practice:

• Good-quality protein stays. The belief that older dogs need less protein "to spare the kidneys" did not hold up: in a dog with healthy kidneys, restriction only accelerates muscle loss.
• Calories are trimmed from fat and portion size, not from protein. Extra weight in an old dog means joint load, breathlessness and worse tolerance of anaesthesia.
• Joints. If the dog struggles to get up and limps, the bowl is not the answer: the change is seen on x-rays of legs and joints, and diet works here only through weight.
• Thirst. A senior dog drinking noticeably more is investigated before the food is changed — see a dog drinking a lot.

If an old dog eats little, the mouth and temperature come before a change of flavour. Persistent refusal is covered in dog not eating.

Feeding an Older Cat: Kidneys, Thyroid and Weight

Cats follow a different order. The two commonest age stories are chronic kidney disease and hyperthyroidism, and both open the same way: the cat loses weight while still eating well.

• Kidneys. With confirmed kidney disease the diet is rebuilt properly — details in feeding a cat with CKD. Before confirmation there is no reason to move a cat onto a renal diet "preventively".
• Thyroid. Hyperthyroidism in older cats causes weight loss, night-time yowling, thirst and vomiting. It is treated, not fed; food only supports.
• Weight. A cat losing weight always means a work-up, not a new packet. Causes are collected in a cat losing weight.
• Thirst. A cat emptying the water bowl is an early sign of kidneys, diabetes or thyroid — see a cat drinking a lot.
• Bladder. Older male cats bring a different story — crystals and stones, where the table is the opposite one, covered in cat urinary stone diet.

A senior cat eating little is not being difficult: a tooth may hurt, kidneys may cause nausea, constipation may block the way. See why a cat is not eating.

Feeding a Diabetic Cat and a Diabetic Dog

Diabetes in cats and dogs is two different diseases with two different tables, and that is the key point of this section.

The cat. Feline diabetes resembles human type 2 and is tied to excess weight. A diet low in carbohydrates and high in protein lowers insulin requirement, and in a proportion of cats treatment leads to remission, with insulin eventually withdrawn. Wet food usually suits better simply because it contains less starch. Any change of food changes the insulin requirement, so food and dose are never changed on the same day.

The dog. Canine diabetes resembles type 1 — there is almost no insulin of its own, and no diet removes it. What matters is predictability: equal portions, equal times, feeding tied to the injection schedule, no sweet treats in between. Fibre helps smooth the rises. A diabetic dog that suddenly stops eating is an emergency, not a missed meal.

Doses, drugs and protocols are outside this article: a vet sets them from a glucose curve, and they do not follow from a single test.

Anaemia in an Older Cat: What Food Can and Cannot Do

Anaemia is a finding, not a disease, so choosing food "for anaemia" without knowing its source is pointless. The vet first splits it in two:

• Regenerative — the bone marrow responds, reticulocytes are high. Blood is being lost or destroyed: bleeding, parasites, immune destruction of red cells.
• Non-regenerative — no response. In cats this is most often chronic kidney disease (too little erythropoietin), chronic inflammation or viral infection.

Iron helps in one scenario only — true iron deficiency, which in cats almost always means hidden chronic blood loss rather than a poor bowl. So food matters here mainly by being palatable, digestible and sufficient in calories, so the cat holds weight while the cause is found.

Moving an Older Pet Onto a New Diet

An abrupt change in an old animal often ends in vomiting, diarrhoea and refusal — after which the owner is sure the food "did not suit". The switch is done over 7–10 days by mixing in a growing share of the new food. Weigh before and a month after. If a cat refuses a therapeutic diet, do not force it: a starving cat is more dangerous than an imperfect food. How an everyday diet is chosen at all is covered in choosing cat food.

Small Pets and Horses Age Differently

In rabbits, rodents and tortoises age shows first through teeth and digestion, and they hide illness until late — typical situations are gathered in rabbit and rodent diseases. Older horses have their own list: teeth, metabolism, hooves; what the blood shows there is covered in horse blood test.

When Not to Wait for a Routine Visit

• the pet has not eaten for over a day (in a cat this quickly damages the liver);
• visible weight loss with a normal appetite;
• a sudden rise in thirst and urine volume;
• lethargy, unsteady gait, pale or yellow gums — see a lethargic cat;
• vomiting more than twice a week in a senior cat — that is a symptom, not "hairballs".

If the form is already in hand and you want each line explained for the species and the age, upload it to pet results interpretation: the analysis explains which markers call for a change of diet and which call for a work-up. How that differs from a consultation is described in online vet results review. For an image, use pet imaging interpretation.

This article is informational. Diagnosis and treatment of your pet are the job of a veterinarian.