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.