All Bunged Up: Unclogging The Constipated Cat - DVM360

Newly updated client handout

We worked with Dr. Margie Scherk to update a client handout on feline constipation. Get it right here.

Straining in the litter box-possibly even crying out or leaving unwelcome hard pellets around the home-constipated felines are uncomfortable. And constipation can interfere with a cat's appetite and even result in vomiting. Traditional approaches to this hard problem include administering enemas, laxatives to soften the stool or increase contractions, dietary fiber, and promotility agents. Could we be missing something really basic? And when should we be concerned about long-term effects of constipation?

CAUSES OF CONSTIPATION 

Constipation is a clinical sign that is not pathognomonic for any particular cause. Most commonly, constipation is a result and sign of dehydration. The body is 65% to 75% water, depending on a cat's age and percent body fat. Homeostasis attempts to maintain a consistent cellular and extracellular environment. When cells become dehydrated, the body takes steps to correct the fluid deficit. Drinking more and concentrating urine are helpful, but once those capabilities have been maximized, water is reabsorbed in the colon, resulting in drier stool that is harder to pass. Bearing this in mind, medical therapy might not be the best initial therapeutic approach.

Other causes of constipation include problems that result in obstruction (either mechanical or functional), painful defecation, stress within the home environment (social or a dirty toilet), and possibly metabolic disease (Table 1). 

EVALUATING THE PATIENT

History

Given the myriad possible causes as well as concurrent problems, getting an appropriate history is very important. Clients may misinterpret stranguria as tenesmus. Not only is asking about the cat's current diet (type, frequency, appetite) important, but also be sure to ask questions to determine whether the patient might be dehydrated (due to decreased intake or increased water loss), may have orthopedic pain, or may be disinclined to use the litter box because of social or toileting factors (fear, unpleasant box). Click here to download a client form with specific questions to ask to address these possible concerns at length. 

Mild constipation does not require a great deal of work-up or treatment, but identifying its causes is relevant for management to reduce the chance for progression. Chronic, recurrent constipation results in dilation of the colon and obstipation, which in some cats becomes irreversible, idiopathic megacolon that is refractory to cure due to loss of normal neuromuscular function (see the sidebar “Chronic course of constipation").1

Physical examination 

On examination, hydration is assessed by assessing skin elasticity plus coat luster, mucous membrane moisture, and eye position (Table 2). Skin elasticity can be misleading in older patients (as well as young kittens) because of age-related changes in body water distribution, elastin, and collagen. Body weight, weight change relative to previous evaluation, body condition score (indicating percentage body fat), and muscle condition score (indicating protein adequacy) help determine progression of dehydration as well as amounts needed to rehydrate the individual. 

Diagnostic testing 

If a cat is experiencing its first episode of uncomplicated constipation, further testing may not be needed and therapeutic rehydration will likely be adequate. For recurrent constipation or when complications such as trauma or degenerative joint disease (DJD) or neurologic signs are present, additional steps are recommended. A minimum database consisting of a complete blood count (CBC), serum chemistry profile, total thyroxine (T4) concentration measurement, and urinalysis should be performed to assess overall metabolic status and to get more information regarding the degree of dehydration.

Abdominal palpation reveals the presence of firm feces in the colon unless the feces is hidden in the pelvic rectum. Radiographs are required to confirm that the firm mass is intraluminal as well as to identify possible extraluminal problems such as obstructive masses or orthopedic or skeletal problems. Spondylosis deformans of the lumbosacral vertebral column as well as pain from degenerative changes in the shoulders, elbows, hips, stifles, or hocks may limit mobility, making it harder to get to the litter box or to squat comfortably. Evidence of pelvic fracture or other poorly aligned fractures may be observed.