Page 927 - Small Animal Internal Medicine, 6th Edition

CHAPTER 51 Weight Loss and Obesity 899

TABLE 51.1 BOX 51.1
VetBooks.ir Differential Diagnosis for Polyphagia and Weight Loss Documented Potential Adverse Effects of Obesity

Decreased life span
DIAGNOSTIC TESTS
ETIOLOGY DEFINITIVE Exacerbation of orthopedic disease, including
osteoarthritis and intervertebral disk disease
Inadequate nutrition Response to diet change Cardiopulmonary dysfunction—impaired lung
and/or increased compliance, Pickwickian syndrome
amounts Exercise intolerance, heat intolerance
Hyperthyroidism Serum T 4 and free T 4 Insulin resistance and predisposition for diabetes mellitus
Hyperlipidemia
concentrations Hepatic lipidosis
Diabetes mellitus Blood glucose Predisposition for pancreatitis
concentration and Problems with constipation
urinalysis Predisposition for feline lower urinary tract disease
Predisposition for urinary incontinence in spayed female
Gastrointestinal Disease
dogs
Parasitism Fecal examination, trial Predisposition for reproductive problems—dystocia
therapy Predisposition for dermatologic problems—seborrhea,
Infiltrative bowel disease: Intestinal biopsy pyoderma
plasmacytic, lymphocytic, Increased surgical and anesthetic risk
eosinophilic, lymphoma
Histoplasmosis Intestinal biopsy,
serology
Lymphangiectasia Intestinal biopsy presence of occult disease, most likely disease involving the
Pancreatic exocrine Serum trypsin-like gastrointestinal tract.
insufficiency immunoreactivity,
response to therapy
Protein-losing nephropathy Urinalysis, urine protein/ OBESITY
creatinine ratio
Hypothalamic mass Computed tomography, Obesity is a clinical syndrome defined by the excess accu-
magnetic resonance mulation of body fat and its consequences. It is defined, as
imaging in people, as a body weight approximately 25% over ideal.
Obesity is considered the most common form of malnutri-
tion in small animal practice. Indeed, studies have shown
that up to 59% of dogs and 63% of cats in various populations
the calculated MER prove equivocal or cannot be attained, are diagnosed with overweight or obesity. The significance
simply feeding more food or calories and reassessing the of obesity pertains to its role in the pathogenesis of a variety
patient’s weight may be illuminative. of diseases and its ability to exacerbate preexisting disease
A complete blood count, serum biochemistry panel, mea- and decrease life span. Obesity has been associated with an
surement of baseline thyroxine concentration, urinalysis, increased incidence of osteoarthritis and other orthopedic
and fecal examination for parasites should be done if the disease, diabetes mellitus, hyperlipidemia, hepatic lipidosis,
history and physical findings are unremarkable. Results of feline lower urinary tract disease (FLUTD), urine inconti-
these tests usually help identify additional specific diagnostic nence in spayed bitches, constipation, non-allergic derma-
tests that may be required to establish a definitive diagnosis. titis, cardiopulmonary dysfunction, respiratory problems,
Inadequate nutrition should be suspected if the diagnostic and increased anesthetic and surgical risks (Box 51.1). In
testing is unremarkable and especially in the face of adequate addition, Scarlett et al. (1998) found a threefold increase
or increased appetite. Changes in the types of foods pro- in risk of death in obese middle-aged cats compared with
vided, daily caloric intake, and feeding routine should be the risk in lean middle-aged cats. Kealy et al. (2002) found
made to ensure that the animal has an adequate caloric that dogs that were kept lean throughout their life lived
intake of a palatable and nutritionally complete and balanced almost 2 years longer than control-group litter mates that
food. Carefully questioning the owner regarding the feeding were overweight. The lean dogs also did not need treat-
environment can also be important, as often subtle food ment for co-morbidities such as osteoarthritis until later
guarding behaviors can be exhibited by both dogs and cats. in life.
The animal’s body weight should be determined 2 and 4
weeks after the start of an appropriate diet. Resolution of Etiology
signs and weight gain confirm the diagnosis. Failure to gain Obesity develops when daily energy intake consistently
weight indicates problems with client compliance or the exceeds daily energy expenditure. Numerous animal and