Colic
Equine colic may arise from numerous sources.  Improper husbandry such as rapid dietary changes ("feeding accident") may cause gas accumulation, dehydration, impaction, and the formation of enteroliths (drying of the ingesta, especially during winter).

Anatomic displacements may cause adhesion formation or vascular accidents, leading to colic.  Strangulation may also occur, causing circulatory compromise.  Strangulation can occur as a result of volvulus (torsion), intussusception ("telescoping"), or hernias (mesenteric lipomas or "strings" are especially common in older horses).

Clinical findings of equine colic include pain, pawing/kicking at the abdomen, restlessness characterised by "up and down" positioning, rolling, flank-watching, "dog-sitting", or a "saw-horse" stance.  Other signs and symptoms of colic include sweating, tachycardia, and hyperpnœa leading to circulatory shock.  Additionally, the animal may go into hypovolæmic or endotoxic shock, characterised by hypotension, discoloured or tacky oral mucosa, poor jugular filling, and cold ears/limbs.  Borborygmi may be loud in spasmodic colic and high-pitched in flatulent colic.  GI sounds are increased frequency in both types of colic.  Palpation is important in determining the site and type of colic, to help determine the presence of gaseous areas (distension), tautness of the intestine, presence of impaction, et c.

Treatment of Equine Colic
The temptation to use atropine (to slow GI motility) should be resisted.  Atropine should NEVER be administered to any animal in which colic is suspected.

Analgesics such as dipyrone, xylazine, flunixin, meperidine, pentazocine, and chloral hydrate may be cautiously administered, but overdose should be avoided.

Ataractics such as acepromazine may be used in mild cases of colic, but the hypotensive effect could result in death of the animal.

Arecoline, a cholinergic agonist, has fallen into disfavour.  However, it may be used cautiously, depending upon the type and severity of the colic.

Aminopropazine (Jenotone®), a phenothiazine derivative, is a smooth muscle relaxant that produces little CNS effect.  It is used to decrease excessive smooth muscle contraction in spasmodic colic.  It is also used for urethral spasms secondary to urolithiasis in dogs in cats.  Aminopropazone may be given slow IV or IM.

Aminopentamide (Centrine®) is an anticholinergic with greater GI and less ophthalmic/salivatory effects, relative to atropine.  It is used for the treatment of acute abdominal/visceral spasms, pylorospasm, hypertrophic gastritis and their associated nausea, vomiting, and diarrhœa.  Adverse effects include dry mouth, dry eyes, blurred vision.  Toxicity may cause urinary retention.  It is available for both oral and parenteral administration.

Isopropamide -- a quaternary anti-cholinergic.  It is available in combination with prochloperazine (a phenothiazine) as Darbid® for the treatment of vomiting and diarrhœa.

Propantheline (Norpanth®) -- a quaternary anti-cholinergic used primarily as an anti-diarrhœal.  It has less ophthalmic effects that atropine.

Most other GI meds used in veterinary medicine (histaminic blockers, anti-nauseants, antacids) are those used in human medicine for similar purposes.

Primary bacterial infections of the urinary tract are common in dogs and relatively uncommon in cats.  Infections secondary to urinary stasis, decreased micturition, or urolithiasis are more common in cats.  UTIs may present as bloody or "ammonia" urine and may cause an animal to break their house- or litterbox-training (especially males).
Renal failure may occur in any animal, given the presence of a toxic compound or disease state.  This problem generally follows the same progression as the human disease states.  The same is true for most micturition disorders.
 

Urolithiasis
Renal or bladder stone formation is common in both cats and dogs.  In dogs, approximately 2.8% of all breeds will experience urolithiasis while 10% of cats will have problems with stone formation.  Recurrence occurs in 50-70% of cats that have had a previous renal stone.  Typically, dogs produce large uroliths while cats produce sand-sized to microscopic stones.  The type of stone (phosphate, oxalate, urate, cystine, carbonate, or silicate) is dependent upon the age, gender, breed, and diet of the particular animal.
 
Canine Urolithiasis
Miniature schnauzers, dachshunds, Dalmatians, pugs, bulldogs, Welsh corgis, basset hounds, beagles, and terriers are all predisposed to stone formation.  Urethral stones are the most common canine stone formed.

Shepards and larger breeds typically form silicate stones with spicules ("jack" stones) while Dalmatians more often form urate stones.  Only male dogs will form cystine stones (a sex-linked characteristic).  Males less that 1 year old and females are more likely to form struvite (magnesium-ammonium-phosphate) stones.

Treatment of canine urinary tract stones is primarily supportive with large amounts of fluids and electrolytes being the mainstay of therapy.  If the animal is unable to pass the stone, surgical removal under anæsthesia may be required.
 

Feline Urolithiasis
Cats with urinary stone formation will typically squat and strain in an attempt to urinary.  They will also typically lick the urogenital area (this is especially true of indoor cats).  More than 90% of feline stones are struvite, however 3-5% of feline stones will be gelatinous plugs with a largely organic matrix.  These latter stones are toothpaste-like in their composition and occur predominantly in the urethra.  Stone formation in many cats may be secondary to a high magnesium diet.

Given the higher incidence of stone formation in cats, a special diet has been formulated, the feline urologic syndrome (FUS) diet for cats that have had a positive diagnosis of stone formation.  This diet is fatty, since less fat in the diet will increase the amount of water in the fæces (to soften the fæces -- fats contribute to the softening of feline fæces, if a diet is low in fat, then water must be used).  The fatty diet will provider softer fæces, allowing the water to be excreted renal, thus increasing the water in the urine and increasing the likelihood of stone dissolution or prevention.

FUS Diet
1 lb of ground beef (not chuck) braised (not drained, to preserve the fat)
1/4 lb liver, raw or braised
1 C cooked rice
1 tsp cooking oil
1 tsp limestone (calcium carbonate), ground eggshell, or eight Tums®
2-3 oz water (optional, if the cat prefers moist food).
Yields 1 3/4 lb of food, with the serving portion of 1/4 to ½ lb per cat daily.