Introduction

• Inappetence means reduced appetite.
• Anorexia means complete lack of eating.
• Both are common signs but don't specifically point to a disease.
• They might indicate nausea.
• Inappetence is not the same as being picky about food.
• Small breed dogs often have picky appetites.

Differential Diagnosis

• Inability to smell food, e.g. cat flu
• Pyrexia
• Pain
• Dental disease
• Gastrointestinal disease, especially foreign bodies, intestinal neoplasia, severe gastroenteritis, intussusception
• Renal failure
• Hepatic disorders
• Pancreatitis
• Heart failure
• Anaemia
• Neoplastic disease
• Metabolic abnormalities, e.g. hypokalaemia,
  hypercalcaemia, hypoadrenocorticism

Diagnostic Approach

• Obtain a detailed history including duration of reduced appetite, percentage of normal daily intake eaten, weight loss, and drinking habits.
• Perform a thorough physical examination, evaluating all body systems.
• Pay special attention to the abdomen for any masses.
• Assess body condition score, hydration status, and signs of underlying disorders.
• The diagnostic approach depends on whether specific signs of illness are present.
• If there are no specific clinical signs and inappropriate diet is ruled out, a blood sample should be taken for haematology and biochemistry.
• Biochemistry should cover urea, creatinine, albumin, globulin, liver enzymes, dynamic bile acids, sodium, potassium, calcium, phosphorus, and glucose.
• Urinalysis, including specific gravity, dipstick examination, and sediment examination, can be helpful, especially if azotaemia is detected in serum biochemical testing, aiding in distinguishing between pre-renal and renal azotaemia.
• If haematology, biochemistry, and urinalysis results are normal, survey radiographs of the abdomen and chest are recommended.

Treatment

• Identify and treat the underlying cause to restore appetite.
• Offer small meals of warmed, palatable food like boiled chicken or fish during recovery.
• Hand-feeding can be helpful, but avoid force-feeding to prevent food aversion.
• Some pets, particularly cats, may not eat while hospitalized, possibly requiring early discharge decisions.

What to do if animal not responding to treatment ?

• Complete anorexia for more than three days in cats, or five days in dogs, requires urgent intervention.
• Hospitalization and supportive care are necessary, especially in cats to prevent hepatic lipidosis.
• IV fluids may be needed to treat dehydration and provide maintenance fluid requirements.
• Address any additional problems such as hypokalemia as appropriate.
• Nutritional support should primarily be through the enteral route, allowing absorption via the gastrointestinal tract.
• Calculate daily caloric requirements for hospitalized dogs and cats using the formula: (30 × body weight in kg) + 70.

• If the patient continues to be anorexic, tube-feeding is recommended.
• Naso-esophageal tubes are well-tolerated and relatively easy to place, suitable for short-term nutrition in non-vomiting patients without esophageal disease.
• Patients can still eat voluntarily with these tubes.
• Syringe feeding may be tolerated by some patients but should only be done by competent individuals due to the risk of aspiration.
• Syringe feeding should be discontinued if the patient appears to resent the procedure.

• Appetite stimulants may be beneficial and include intravenous diazepam for cats, or oral cyproheptadine or mirtazapine for dogs or cats.
• Suspected nausea can be treated with maropitant or metoclopramide.
• Vitamin B12 supplementation might be considered, especially in patients with low B12 concentrations due to gastrointestinal disease.
• Corticosteroids should not be used empirically as appetite stimulants. They should be reserved for patients with identified corticosteroid-responsive diseases or for palliative treatment in very sick patients if further investigations/treatments are declined by owners.

• Parenteral nutrition (IV route) is suitable for only a small number of patients with severely compromised intestinal function and is not typically done in general practice.
• Isotonic glucose-containing IV fluids and amino acid supplements provide only a small portion of daily caloric needs and should not replace adequate enteral nutrition.
• If the patient fails to eat after treating an identified underlying cause, clinicians should search for additional causes.
• Repeat physical examination to ensure specific clinical signs haven't been overlooked or developed.
• Re-evaluate blood test results and radiographs to ensure nothing has been missed.