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Anorexia

BASICS

DEFINITION/OVERVIEW

Anorexia is the lack of appetite or intake of food, and does not define an underlying cause. Many pathological and even physiological conditions can result in decreased food intake. Anorexia is distinct from decreased appetite, which is also known as hypophagia.

ETIOLOGY/PATHOPHYSIOLOGY

Anorexia may be a normal physiologic/behavioral occurrence during certain times of the year (e.g., brumation, estivation, reproductive season).

Pathologic causes of anorexia may stem from either GI or extra‐GI disease (e.g., any painful condition or systemic illness).

Improper husbandry, and offering the wrong type and size of food, may also lead to anorexia.

Anorexia may often result in dehydration, as many reptile’s primary fluid intake is through food items.

Prolonged anorexia may lead to hepatic lipidosis, which may result in nausea, leading to continued lack of food intake.

Nutritional imbalances and metabolic derangements can occur with chronic anorexia and cachexia may ensue.

Primarily, the gastrointestinal and musculoskeletal systems are affected with anorexia.

Animals that are not consuming food for prolonged periods of time may not defecate significant amounts.

As the body begins to break down adipose tissue stores and muscle, bony prominences become more obvious as body condition decreases.

SIGNALMENT/HISTORY

Anorexia has no age or sex predilection.

It is important to differentiate physiologic/behavioral anorexia from that caused by an underlying pathology or disease process.

CLINICAL PRESENTATION

An isolated incident or occasional episodes of anorexia in otherwise healthy animals may be inconsequential, especially in animals presenting in good body condition.

Decreased food intake over an extended period.

Clients may report repeated attempts at feeding.

Clinical signs of chronic anorexia include a decreased body condition score with prominent bony protuberances, dehydration, and muscle wasting.

RISK FACTORS

Any disease process could result in anorexia.

Different types of stress may also result in decreased food intake.

Husbandry

Adjusting to captivity—often seen in newly acquired animals. A period of time for acclimation may be necessary before an animal feels secure enough to start eating on its own.

Improper husbandry—inappropriate environmental temperature or humidity, inappropriate food items (type and/or size), malnutrition, inadequate exposure to UVB lighting, poor water quality, overcrowding, rapid change of diet, lack of provision of hiding areas.

Stress—social or environmental.

Others

Physiologic

Cardiovascular disease: cardiomyopathy, congestive heart failure

Reproductive activity: gravid females, breeding males

Reproductive disease: pre‐ or postovulatory dystocia

Respiratory infections: upper and lower respiratory tract infections; mycoplasmosis

Viral infections: herpesviral infections in Testudo spp; ranaviral infections; iridoviral infections

Fungal infections: fungal pneumonia

Systemic illness: septicemia

GI disease: stomatitis, foreign bodies, neoplasia, intussusception, gastroenteritis, constipation, prolapses

Parasitic disease: ectoparasites and endoparasites

Neurologic disease

Toxic diseases

Urogenital: cystoliths; prolapsed phallus; renal disease

Metabolic: nutritional secondary hyperparathyroidism; hypovitaminosis A

Any potentially painful condition: ophthalmic disease, orthopedic conditions (including shell fractures), cellulitis, trauma

DIAGNOSIS

DIFFERENTIAL DIAGNOSIS

Conditions that result in failed food prehension (disorders of the tongue or oral cavity) or processing may result in animals that attempt to eat (have an appetite) but are unable to do so successfully.

Hypophagia may be mistaken for anorexia in certain circumstances.

DIAGNOSTICS

Diagnostic procedures should be tailored towards identifying the underlying cause of the anorexia and identifying potential negative sequelae (e.g., hepatic lipidosis).

Baseline Blood Work

CBC, PCV, TS, biochemistry

Findings on complete blood count and biochemistry panels are usually non‐specific but may be suggestive of an underlying disease process(es) resulting in the observed anorexia.

Bile acids and liver leakage enzymes (AST) may be increased if hepatic lipidosis is present secondary to prolonged anorexia.

Imaging

Radiography can help identify abnormalities of the GI tract such as foreign bodies and masses. Ultrasound and CT can provide more detailed information about possible hepatic lipidosis, ileus, and coelomic masses.

Other Tests

Additional diagnostics, including infectious or parasitic disease testing, may be warranted based on patient history and physical examination findings.

The presumed underlying causes should be thoroughly investigated.

PATHOLOGICAL FINDINGS

Findings depend on underlying cause of the anorexia.

Hepatic lipidosis may be suspected based on the findings of advanced imaging or biochemistry evaluation.

TREATMENT

APPROPRIATE HEALTH CARE

N/A

NUTRITIONAL SUPPORT

Nutritional support should be started in anorectic animals that have lost 10% of their body weight acutely (7 days or less) or 20% chronically (longer than 7 days).

This weight loss must also be monitored together with an assessment of body condition (BCS).

Anorectic animals with a BCS of 2/5 or lower may be immediate candidates for nutritional support.

Animals should be housed in appropriate environments and maintained at their preferred optimum temperature zones, to facilitate proper utilization of the provided nourishment.

Liquid diets may be provided via gavage in smaller animals.

Placement of an esophagostomy tube should be considered for long‐term support and to minimize stress of force feeding.

Although poorly understood in veterinary medicine, the potential exists for refeeding syndrome in chronically anorectic patients, necessitating careful planning of nutritional support in these animals.

Recommendations include feeding chronically anorectic animals half their calculated energy requirements initially, then slowly increasing up to the full energy requirement over 7–10 days.

CLIENT EDUCATION/HUSBANDRY RECOMMENDATIONS

The clinician should perform a thorough review of the patient’s current husbandry, including feeding.

It is important to ensure that a proper diet of an appropriate size is being offered.

The diet must be presented to the animal appropriately (e.g., feeding diurnal animals during daylight hours, offering prey on land vs. in the water or vice versa).

Any husbandry or dietary deficiencies should be corrected.

Clients should be notified that offering live food items to anorectic animals could result in rapid, serious injury to their pet secondary to prey attacks.

For most cases, live prey should not be offered to chelonians without direct supervision.

MEDICATIONS

DRUG(S) OF CHOICE

Commercial, high‐calorie formulations designed for nutritional support are recommended when feeding anorectic crocodilians.

Alternatively, a slurry can be made with a commercial pelleted diet.

PRECAUTIONS/INTERACTIONS

Exercise caution when force feeding, to prevent oral, esophageal, or gastric trauma.

Be careful not to administer too large a volume of nutritional formula in small patients.

Feed 1–3% of body weight initially to ensure the animal will tolerate the feeding.

FOLLOW‐UP

PATIENT MONITORING

Individuals should be monitored for resolution of anorexia following correction of any husbandry and dietary deficiencies.

Serial imaging and blood chemistry evaluation may be considered to monitor for development or resolution of secondary liver diseases such as hepatic lipidosis.

In patients with esophagostomy tubes, the tube should be monitored for clogging and the stoma regularly evaluated for signs of infection.

EXPECTED COURSE AND PROGNOSIS

Anorexia may continue until the underlying reason is identified and treated, if applicable.

Prognosis for resolution of anorexia depends on the severity of the underlying cause.

MISCELLANEOUS

COMMENTS

Simply providing appropriate husbandry will help prevent many causes of anorexia in chelonians.

Prompt diagnosis of true anorexia enables initiation of proper nutritional support and may prevent formation of hepatic lipidosis, which can perpetuate the lack of appetite.

Supportive care should be continued while an underlying cause for the anorexia is identified and corrected.

Gravid individuals may decrease their amount of food consumption from lack of coelomic space for GI distension.

Animals that are anorectic from an underlying pathologic condition may cease or abort reproductive activity due to preferential allotment of energy for other physiologic functions.

ZOONOTIC POTENTIAL

N/A

SYNONYMS

Anophagia

Aphagia

Inappetence

ABBREVIATIONS

AST = aspartate aminotransferase

BCS = body condition score

CBC = complete blood count

CT = computed tomography

GI = gastrointestinal

PCV = packed cell volume

TS = total solids

UVB = ultraviolet B