Page 793 - Problem-Based Feline Medicine

35 – THE CONSTIPATED OR STRAINING CAT 785

Serum biochemistry analysis may detect electrolyte lactulose on a daily basis for the prevention of con-
disturbances (e.g. hypokalemia) contributing to stipation.
reduced evacuation of feces. ● Emollient laxatives act as anionic detergents to
increase the miscibility of water and lipid in the
bowel contents, enhancing lipid absorption but
Differential diagnosis
impairing water absorption. Dioctyl sodium sulfos-
Constipation can usually be easily differentiated from uccinate (Colace, 50 mg PO q 24 h) and dioctyl cal-
other causes of straining, such as lower urinary tract ium sulfosuccinate (Surfax, 50 mg PO q 12–24 h)
disorders, by physical examination. are two examples of this class of drugs. Care
should be taken that the cat is well hydrated
prior to the administration of these agents, as
Treatment
they retard the absorption of water from the intes-
Therapy is dependent on the severity of constipation tine.
and the underlying cause. Any underlying causes ● Lubricant laxatives act by easing fecal passage
such as litterbox problems, intraluminal or extraluminal and decreasing water absorption from the colon by
obstructions, orthopedic disorders, anal inflammation creating a coating layer on the mucosa. These
or perineal hair matting should be corrected. agents (e.g. mineral oil or petrolatum products such
as Laxatone or Kat-A-Lax) are suitable only for
Animals with mild to moderate constipation may be
mild constipation, or for regular use to prevent
treated as outpatients.
constipation in mildly affected cats.
● Tepid water enemas (5–10 ml/kg q 8–24 h)
or commercially available pediatric enemas If there is obstipation, manual extraction of feces
(Microlax, 1–2 tubes/cat) should be administered as under general anesthesia is usually required to treat
needed to facilitate fecal breakdown and passage. obstipation, as the condition is too severe to respond to
● Dietary fiber serves to enhance fecal bulk, and has enemas alone.
laxative effects. These effects are due to increased ● Balanced fluids (e.g. Lactated Ringer’s Solution,
fecal water content, decreased intestinal transit time Plasma-Lyte A or Normisol-R) should be adminis-
and increased frequency of defecation. A number of tered to rehydrate and correct fluid deficits. This is
fiber supplements are available, including psillium particularly important in older cats or if general
(Metamucil, 1–4 tsp mixed with food at each meal), anesthesia is required for treatment. An endotra-
or wheat bran (1–2 tsp mixed with food at each cheal tube should be placed to prevent inhalation
meal). Some cats find the sweetness of canned pneumonia as manipulation of the colon may
pumpkin or canned creamed corn (1–4 tbsp induce vomiting.
mixed with food at each meal) makes a more palat- ● After the distal colon has been lubricated by a warm
able fiber supplement. water or saline infusion, forceps are inserted and
● Lactulose (0.5 ml/kg PO q 8–12 h) is a hyperos- used to carefully grasp or break down fecal mate-
motic laxative which softens feces by reducing rial. A constantly twisting motion, clockwise and
water absorption in the colon. Milk may be a more counterclockwise, should be used to prevent the
palatable alternative, as the lactose in milk is indi- forceps accidentally grasping the colonic
gestible in most cats, causing it to act as a hyperos- mucosa. Alternatively, a spoon-shaped instrument,
motic agent. specifically designed for the purpose, may be used
● Cisapride (2.5 mg PO q 12 h) is a gastrointestinal to gradually break down the fecal mass, while con-
prokinetic agent, which stimulates colonic motility nected to a faucet to provide a steady trickle of
from the gastroesophageal sphincter to the descend- warm water into the colon.
ing colon. It is believed to enhance cholinergic ● If any bleeding is noted on manual fecal extrac-
neurotransmission in the gastrointestinal tract tion, the procedure should be aborted to mini-
via stimulation of enteric neuronal serotonin mize the risk of intestinal perforation or
receptors. Cisapride may be used alone for the devitalization of the colonic mucosa. It may be
treatment of mild to moderate constipation, or with preferable to perform manual extraction over