This is a common problem that all dog owners will worry about and experience at some point, so it’s important to know when to worry and when to wait. 

Firstly, consider your own dog and their general health. Is your dog young and generally fit and well? Or are they older and have other known health issues? Is your dog behaving unwell or are they bright, happy and playful? Does your dog have any outward signs of illness? Are they being sick or experiencing diarrhoea? Are they salivating lots, suggesting nausea? Some of the (many) reasons your dog may not eat are: 

Stress

Some dogs are really sensitive to change. Change in routine can upset a dog and put them off their food. Some dogs need a little time to settle and get used to a new environment or routine before they feel comfortable enough to eat well. An obvious example of this is with a new puppy, leaving their mother and joining their new family, or any dog after moving home with their owners to a new area. Adding a new family member (having a baby or having someone visit) can also be a great source of stress to our furry friends who may then, as a response, go on hunger strike for a little while. 

Make sure your dog has plenty of space to get used to changes, some one-on-one time with you and plenty of reassurance to help them cope with new situations. You could also consider supplements (e.g. Calm aid, Zylkene) or plug ins (Adaptil, PetRemedy) to help your dog adjust smoothly. 

A change in diet 

It is advised that any diet change is done slowly to make sure your dog isn’t stressed by the change but also to prevent tummy upset. Your dog may stop eating if they experience diarrhoea or vomiting or just get a sore tummy from abrupt diet changes. They may also not like the new food. 

Pain 

Your dog could experience pain interfering with the desire to physically consume food

Oral Pain 

Best DNA Kit 2024
Koko DNA Test for Dogs Advanced (+175 Breeds, Health + Traits Reports)
VetHelpDirect Rating:
4.7
Discover Your Dogs DNA
We earn a commission if you make a purchase, at no additional cost to you.

Such as dental pain, gingivitis (gum inflammation), orofacial pain, pain in the temporomandibular joint TMJ (jaw itself). If it hurts to eat, even if your dog is hungry, they would be discouraged from doing so. The presentation for painful food avoidance tends to be gradual so they would usually demonstrate a reduced or picky appetite prior to stopping eating entirely. 

Abdominal pain 

You know yourself if your tummy is sore, you’re not going to be diving into dinner. So why might your dog get a sore tummy? Well, the two most common reasons are:

Dietary indiscretion

Some dogs are avid scavengers and like to eat things they shouldn’t around the house or on walks. Dietary indiscretion can lead to abdominal discomfort and/or possibly nausea, so your dog may not want his usual food for a day or so. They may also experience diarrhoea with or without vomiting as the gastrointestinal tract becomes inflamed and upset by the foreign material. 

If your dog vomits for over 24 hours or more than 4 times in a row, or if diarrhoea persists for over 2 days, contains blood or your dog is unwell with these symptoms, you should immediately seek veterinary attention as it may be a symptom that either:

  • your dogs’ body isn’t coping; or
  • that a foreign item has become stuck causing a blockage or FOREIGN BODY; or
  • they have gotten into something TOXIC requiring immediate veterinary attention. 

Pancreatitis 

The pancreas has a number of functions – one of which is to release enzymes to break down fat and protein that is eaten. Pancreatitis occurs if the pancreas is inflamed or diseased due to either infection, an excessive fatty meal, a blockage of enzymes etc, the pancreas can give out too many enzymes which creates problems in the upper intestines. 

Symptoms tend to be a very painful upper abdomen (sometimes dogs try to alleviate this by adopting the “prayer position”), vomiting, diarrhoea and anorexia. This is a complex condition to diagnose and treat and so veterinary advice should be sought if your dog has symptoms. 

Infection

Again, symptoms here tend to be diarrhoea and/ or vomiting persisting more than 48 hrs with an unwell dog. However, any illness causing a high fever may also result in loss of appetite, even without any other symptoms.

Diseases involving the organs

UK Fast & Free Delivery Available
Pet Medication, Pet Food & Products, Veterinary Prescriptions
VetHelpDirect Rating:
4.8
Shop Now
We may earn a commission for any purchase you make

Examples of disease processes include, kidney disease, liver disease, heart disease, lung disease, gastrointestinal disease, diabetes, Addisons disease etc. Any disease in which an organ of the body isn’t functioning as it should, can create a problem. There are usually other symptoms associated with these diseases other than just not eating so your dog will be visibly unwell. 

Kidney and liver disease 

The kidneys and liver, in simple terms, are both involved in “cleaning the blood”, so if they are not functioning properly then toxins build up in the body leading to nausea and a general feeling of being unwell. Symptoms include excessive thirst, loss of appetite, sometimes pale or yellow gums (jaundice), nausea, vomiting and anorexia. 

Diabetes 

A process in which the pancreas doesn’t produce enough insulin, or the body doesn’t recognise the insulin and so glucose (energy) isn’t able to be used properly in the body cells. The body looks elsewhere for energy sources and so breaks down muscle and fat in a process called KETOSIS. This leads to a very unwell dog often off their food but also quiet and weak, vomiting, anorexia, an increased thirst and urination. This is an emergency situation. 

Addison’s disease 

Addisons disease is a disorder of hormonal imbalance in the body. The hormones are usually produced by the adrenal glands and are vital in regulating the body’s fluid balance and therefore the bodys’ function. Symptoms include lethargy, vomiting, diarrhoea, increased urination and anorexia. 

Heart and lung disease 

During heart or lung failure the body is trying to get oxygenated blood around the body and struggling to do so. Symptoms therefore tend to be an increased heart rate and breathing rate in an attempt to rectify the struggling organs inefficiency. Due to the body focussing on surviving, dogs tend to be unable to eat. 

In summary

If your dog hasn’t eaten for over 24hrs, it is prudent to get an examination with your veterinarian. As you can see, there are a myriad of reasons your dog could be not eating. Your vet will perform a physical exam to exclude painful conditions and possibly blood tests and maybe imaging such as x-rays or ultrasound imaging depending on the findings of their physical exam alongside your pets’ clinical history. 

Not eating for a single day without clinical signs of being unwell isn’t generally a concern, however, things can change rapidly with dogs and so keeping a close eye on them and making sure they recover quickly is important. 

Further reading: 

Best Dog Healthy Dog Treats - Staff Pick
Greenies Pill Pockets for Dogs - Capsule Size Natural Soft Dog Treats with Real Peanut Butter (60 Treats)
VetHelpDirect Rating:
4.8
View On Amazon
We earn a commission if you make a purchase, at no additional cost to you.
Best Everyday Dog Toy 2024
Chuckit Indoor Fetch Ball Dog Toy - Orange and Blue
VetHelpDirect Rating:
4.6
See More Dog Toys Here
We earn a commission if you make a purchase, at no additional cost to you.