Let’s Dish: 7 Reasons Why Your Pet’s Appetite or Thirst Has Changed

Your pet’s eating and drinking habits provide your Animal Hospital of Parkland veterinarian with important clues about their overall health. Sudden or uncharacteristic changes can mean your pet is naturally correcting an internal imbalance (e.g., avoiding food because of motion sickness, or rehydrating themselves after outdoor exercise), or a warning that they have a more serious and persistent internal condition.

If you’ve noticed that your pet’s food or water consumption has changed, check out our guide to common causes and how and when to help your pet.

Bowled over: Monitoring your pet’s normal behaviors

The Animal Hospital of Parkland team recommends that you regularly monitor your pet’s daily food and water intake so you will notice subtle changes and seek prompt veterinary care. Measuring and observing your pet’s daily portions not only helps you identify early warning signs, but also keeps your pet heathy by preventing weight gain, boredom-based eating, and picky behaviors.

We recommend:

Using a measured scoop to portion your pet’s food
Replacing automatic feeders and waterers with standard bowls
Separating pets during mealtime to prevent food theft and bullying
Periodically assessing your pet’s water intake by filling the bowl with a measured amount (i.e., in ounces) and remeasuring the volume after 24 hours
Watching for atypical behavior, such as counter-surfing, getting into the trash, drinking from puddles, or inter-pet aggression (i.e., bullying)
Noting other potentially related signs, such as vomiting, diarrhea, increased or decreased urine or stool, painful posture, or lethargy

Note any changes in your pet’s behavior or food and water consumption on a calendar. If these changes become a trend or they are accompanied by other clinical signs, schedule an appointment at the Animal Hospital of Parkland.

7 Common reasons for altered appetite and thirst in pets

Unusual food and water intake changes can be linked to myriad health and behavioral conditions in pets, but our team has narrowed down our list to the most common causes, which range from normal and unconcerning to serious.

Although the following seven causes include a range of potential explanations for your pet’s unusual behavior, a complete veterinary examination and diagnostic testing are necessary to determine the true source of a pet’s unusual appetite or thirst.

Your pet is dehydrated — Dehydration occurs when pets lose more water than they take in. Mild dehydration can occur if your pet is without water for a period of time—especially during hot weather—or has recently exercised vigorously.

Hydration loss can also occur quickly through vomiting, diarrhea, and excessive urination, which can be caused by underlying illness or disease.

Your pet is overheated — Pets experiencing heat exhaustion or heatstroke pant rapidly to cool themselves, which increases their demand for water. Overheated pets may also vomit and have diarrhea, which hastens fluid loss and increases your pet’s thirst. Severely affected pets require emergency veterinary intervention, while healthy pets may voluntarily reduce their food intake during warm summer months to avoid a rise in internal temperatures caused by the digestive process.
Your pet is nauseated — Nausea in pets can lead to food aversion and cause previously food-motivated pets to leave their bowls full. Nausea can be caused by gastritis, dietary indiscretion, motion sickness, bloat, foreign body ingestion, pancreatitis, liver or kidney disease, and certain medications.
Your pet has a urinary tract problem — Your pet’s upper and lower urinary tracts include the kidneys, ureters, urinary bladder, and urethra. Pets may be more thirsty and urinate more frequently because of kidney failure or a urinary tract infection (UTI), although a UTI can cause decreased thirst in some pets. Pets in late-stage kidney failure will also experience appetite loss.
Your pet has diabetes — Diabetes occurs when pets cannot properly use glucose (i.e., sugar), because their pancreas is not producing enough insulin. The condition can occur at any age, but is more common in senior dogs and cats. Increased thirst and urination, as well as an increased appetite, are hallmark diabetes signs in pets.
Your unspayed female pet is pregnant or has an infected uterus — Pregnant pets may experience an increased appetite, as well as weight gain and abdominal swelling. Unspayed pets can experience a false pregnancy, with similar signs, or pyometra—a potentially life-threatening condition in which the uterus fills with pus. Pyometra warning signs include increased thirst and urination, appetite loss, and lethargy.

Your pet has a hormone-related disorder — The endocrine system is responsible for hormone production and circulation. The hormones regulate various important processes throughout your pet’s body. When hormone levels are too low or too high, pets can experience drastic appetite and thirst changes. Common endocrine disorders include:
- Hyperthyroidism in cats — Affected cats lose weight, despite a ravenous appetite, and have increased thirst, urination, and vomiting, and hyperactivity.
- Cushing’s disease — Cushingoid pets have elevated cortisol (i.e., a steroid hormone) and experience extreme thirst, increased urination, skin changes, and muscle loss.

Your pet’s eating and drinking habits are more than nourishment and hydration—they tell a story about your pet’s internal health. If your pet’s appetite or thirst has unusually changed or they show disease-specific signs that we outline above, contact the Animal Hospital of Parkland. Our caring team will gather your pet’s information over the phone and advise you if your pet’s behavior is normal, merits further monitoring, or requires a veterinary evaluation.