Ammonium Chloride

Ammonium chloride is an acidifying salt used orally to lower urinary pH in selected veterinary patients. Its role is most relevant when a urinary disorder benefits from acidification, including prevention of certain calculi in ruminants. Whether it helps depends on stone composition, diet and the patient’s acid-base status.

It does not act as a general urinary antiseptic and does not dissolve every type of urolith. Historical use for chronic urinary infection reflects modification of the urinary environment rather than direct elimination of the infecting organism.

Group

Urinary acidifier

Mechanism of Action

Ammonium chloride dissociates into ammonium and chloride ions. Hepatic metabolism of ammonium to urea consumes bicarbonate and imposes an acid load, reducing the body’s alkaline reserve. Renal handling of this load increases acid excretion and can lower urinary pH.

A more acidic urinary environment reduces the tendency of some phosphate-containing minerals to precipitate and can increase the solubility of susceptible calculi. The direction of benefit depends on mineral chemistry: acidification appropriate for one stone type can be inappropriate for another.

The resulting change in acid-base balance is systemic as well as urinary. Excessive exposure can therefore cause metabolic acidosis rather than merely producing a lower urine-pH reading. The desired urinary response also varies with the buffering and mineral content of the overall diet.

Dose Rates

Dogs

Use / stage	Dose	Route	Schedule	Instructions
Urinary acidification	100 mg/kg	PO	Every 12 h
Struvite urolith adjunct	20 mg/kg	PO	Every 8 h
Enhanced renal elimination of selected toxicants	50 mg/kg	PO	Every 6 h	Derived from 200 mg/kg/day divided into four equal amounts; select only toxicants for which acidification is appropriate.
Strontium elimination adjunct	0.2–0.5 g/animal	PO	Every 6–8 h	Used with calcium salts.
Oral ammonia tolerance test	100 mg/kg	PO	Once	Maximum 3000 mg/dose; Oral challenge in 20–50 mL warm water or gelatin capsules; sample at 30 and 60 minutes. A non-challenge fasting/postprandial alternative may avoid ammonium exposure.

Cats

Use / stage	Dose	Route	Schedule	Instructions
Urinary acidification - weight-based listing	20 mg/kg	PO	Every 24 h	Mix with food. The separately listed 800 mg/cat amount is not equivalent and is withheld pending clarification.
Urinary acidification - fixed amount listing	800 mg/animal	PO	Every 24 h	An unresolved alternative is 800 mg/cat alongside 20 mg/kg and a household-volume estimate. These are not equivalent; confirm intended amount before use.
Struvite urolith adjunct	20 mg/kg	PO	Every 12 h	Use only when dietary and infection management do not adequately acidify urine; patient must not be obstructed.

Horses

Use / stage	Dose	Route	Schedule	Instructions
Urinary acidification	100–250 mg/kg	PO	Every 24 h
Urinary acidification - broader daily alternative	60–520 mg/kg	PO	Every 24 h	Unpalatable; stomach tube or dosing syringe may be necessary. Diet composition affects response.
Urinary acidification - fixed alternative	4–15 g/animal	PO
Strychnine elimination adjunct	132 mg/kg	PO		No repeat interval specified.

Cattle

Use / stage	Dose	Route	Schedule	Instructions
Urolithiasis prevention	200 mg/kg	PO		Repeat interval is not specified.
Urolithiasis prevention - fixed alternative	15–30 g/animal	PO

Sheep

Use / stage	Dose	Route	Schedule	Instructions
Urolithiasis prevention	300 mg/kg	PO		Repeat interval is not specified.
Urolithiasis prevention - dietary inclusion	Reference only	PO		0.5–1% of daily dry matter; palatability can limit intake. Do not substitute this dietary percentage for mg/kg body weight.

Goats

Use / stage	Dose	Route	Schedule	Instructions
Urolithiasis prevention	300 mg/kg	PO		Repeat interval is not specified.
Urolithiasis prevention - dietary inclusion	Reference only	PO		0.5–1% of daily dry matter; palatability can limit intake. Do not substitute this dietary percentage for mg/kg body weight.

Indications

Urinary acidification for prevention or management of selected phosphate-containing calculi, including urolith prevention in small ruminants.
Adjunctive acidification in selected bladder-calculus dissolution or prevention plans based on the mineral composition.
Historical adjunctive urinary acidification in selected chronic urinary tract infections.

Contraindications

Systemic acidemia.
Use cautiously in renal disease.
Severe hepatic disease, urate calculi or respiratory acidosis.
Generally avoid in uremia; it may worsen existing metabolic acidosis.
Do not give SC, IP or rectally for routine acidification.
Use cautiously with pulmonary insufficiency or cardiac edema.

Interactions

Urine acidification can reduce aminoglycoside or erythromycin activity in urinary infection and increase quinidine elimination.

Adverse effects

Bitter taste and poor acceptance.
High doses can cause acidemia.
Gastric irritation, nausea and vomiting.
Feline urinary acidification increases calcium-oxalate stone risk.

Toxicity

Overdose may cause vomiting, thirst, hyperventilation, arrhythmias and progressive CNS depression with severe acidosis or hypokalemia. Correct acid–base and electrolyte disturbances with close monitoring; IV bicarbonate or acetate and appropriate potassium replacement may be required.

Preparations

Preparation	Form	Strength	Route
Ammonium chloride crystals	Powder	1000 mg / g	PO
Ammonium chloride 200 mg tablet	Tablet	200 mg / tablet	PO
Ammonium chloride 400 mg tablet	Tablet	400 mg / tablet	PO

Monitoring and Administration

Monitor acid–base status and urinary response. Mix with food only when intake remains adequate.

Store crystals tightly closed and protected from light at room temperature.

A historical rectal ammonia-tolerance challenge is 2 mL/kg of 5% solution with samples at 20 and 40 minutes, but routine rectal use is otherwise prohibited. This conflicting procedural route is not offered for calculation.

Monitor urinary pH, with a cited goal at or below 6.5 where acidification is indicated; check blood pH and electrolytes during prolonged treatment or suspected toxicity. An injectable concentrate contains 267.5 mg/mL (5 mEq/mL); no general veterinary IV infusion regimen is established here.