Suspected toxicosis after topical administration of minoxidil in 2 cats

Successful management of minoxidil 5% toxicosis in 2 cats from the same household

OBJECTIVE

To describe the successful management of 2 cats following ingestion of minoxidil 5%.

SERIES SUMMARY

Two 2-year-old neutered male Savannah cats were presented following suspected minoxidil 5% ingestion. Both cats developed significant myocardial injury, and clinical signs were consistent with congestive heart failure, supported by cardiac troponin I concentrations, echocardiogram, and thoracic radiographs. They required vasopressor therapy and were decontaminated with intravenous lipid emulsion therapy. Following decontamination, both cats were successfully discontinued from vasopressor therapy, and their clinical signs resolved within 24 hours. The cats were successfully discharged without long-lasting cardiac compromise. Their echocardiograms and cardiac troponin concentration 7 weeks after discharge were within reference intervals.

NEW OR UNIQUE INFORMATION

This is the first detailed report of the successful management of cats following minoxidil 5% ingestion.

Successful management of suspected minoxidil toxicosis in a cat following accidental dermal exposure

Minoxidil was originally introduced as a potent vasodilator, but is now widely used as a topical treatment for human alopecia. A 4-year-old neutered male Norwegian Forest cat presented with a 2-day history of anorexia, lethargy, and dyspnoea. A physical examination revealed hypothermia, tachypnoea, hypotension, and bilateral pulmonary crackles. The radiographs revealed pulmonary oedema and pleural effusions. The hypotension and pleural effusions exacerbated despite the supportive therapy, and the underlying cause remained undetermined. A further medical inquiry revealed the cat had been exposed to a topical minoxidil solution 3 days before admission. Accordingly, minoxidil toxicosis was managed using both i.v. fluids and vasopressors. Dopamine and norepinephrine were infused for 3 days to normalise the patient's blood pressure and related clinical signs. The cat recovered fully and was discharged 6 days after the minoxidil exposure. This is the first report on the successful management of minoxidil toxicosis in a cat. To broaden our knowledge of minoxidil toxicosis in cats, we have also described the serial changes in the clinical findings of this cat over the treatment period. Furthermore, on the basis of the experience gained from this case, we suggest an optimised management plan for future cases of feline minoxidil toxicosis.

Alopecias in humans: biology, pathomechanisms and emerging therapies

BACKGROUND

The hair follicle is a complete mini-organ with a complex biology. Recent discoveries have shed light on the pathogenesis and genetic basis of a number of hair loss conditions, offering novel treatment alternatives.

OBJECTIVE

To explore the biology and physiology of hair growth, the pathomechanism behind alopecias and emerging therapies.

CONCLUSION AND CLINICAL IMPORTANCE

Hair growth is influenced by numerous physiological moderators. Greater understanding of the biology and physiology of the hair follicle and the pathomechanisms of hair disease facilitates development of targeted treatments. Sublingual minoxidil is a promising therapy in humans where optimised drug delivery enhances efficacy and reduces systemic adverse effects. Janice kinase inhibitors, which disrupt the inflammatory cascade, help maintain the hair follicle, preserve immune privilege, and regrow hair in alopecia areata. As the pathomechanisms of other forms of alopecia become better understood, new targeted therapies with greater efficacy will emerge.

Topical Minoxidil Exposures and Toxicoses in Dogs and Cats: 211 Cases (2001-2019)

Topical minoxidil is a medication for hair loss, initially available in the United States by prescription only and available since 1996 as an over-the-counter product. To determine the epidemiology of minoxidil exposures and toxicoses in dogs and cats, 211 dog and cat cases with topical minoxidil exposure were identified from the American Society for the Prevention of Cruelty to Animals Animal Poison Control Center database. In 87 cases with clinical signs of toxicosis (62 cats, 25 dogs), case narratives were reviewed and coded for exposure-related circumstances. Unintentional delivery, especially while pet owners applied minoxidil for his/her own hair loss (e.g., pet licked owner's skin or pillowcase, pet was splashed during a medication spill), was the most common cat exposure circumstance. Exploratory behavior (e.g., searching through trash) was the most common dog exposure circumstance. Clinical signs occurred in dogs and cats even with low exposure amounts, such as drops or licks. In patients that developed clinical signs, most developed moderate or major illness (56.0% dogs, 59.7% cats). Death occurred in 8/62 (12.9%) cats that developed clinical signs after the pet owner's minoxidil use. Pet owners should be educated on the risk of dog and cat toxicosis from accidental minoxidil exposure.

Dermatological topical products used in the US population and their toxicity to dogs and cats

BACKGROUND

Many dermatological topicals are available for human use and may be toxic to dogs and cats. No epidemiological studies have been performed in the US population on the use of dermatological topical prescription drugs, and their toxicosis to dogs and cats.

OBJECTIVES

Summarize the variety of dermatological topical prescriptions potentially used by pet owners in the United States (US), and describe the epidemiology of dog and cat exposures and toxicities.

ANIMALS/SUBJECTS

A dataset of 10,170 individuals from the National Health and Nutrition Examination Survey (NHANES) representative of 311,065,381 US residents. There were 61,169 dog and cat cases with exposure to dermatological topicals from the American Society for the Prevention of Cruelty to Animals (ASPCA) Animal Poison Control Center (APCC) database.

METHODS AND MATERIALS

Prescription medication data were analyzed from NHANES 2011-2014 survey respondents. The APCC database was searched for records of dermatological topical drug cases between January 2001 and January 2018.

RESULTS

Prescription dermatological topical medications were used by 1.33 ± 0.21% of the US population. Dermatological topical products (177, veterinary and human) resulted in 61,169 exposure calls to the APCC. Clinical signs developed in 38% (22,910). A human-labelled product was involved in 15% (3,463) with 74% (2,545) involving a prescription product.

CONCLUSIONS AND CLINICAL SIGNIFICANCE

Pets in households with humans receiving dermatological prescription topicals may be at risk for toxicosis. Multiple human-labelled dermatological topicals can cause death or major illness to dogs and cats at low dosages. Increased public awareness, especially attention to home storage practices for human-labelled dermatological topicals, may reduce the risk of exposure and toxicosis to dogs and cats.

Successful management of minoxidil toxicosis in a dog

CASE DESCRIPTION A 2-year-old sexually intact female mixed-breed dog was evaluated at an emergency hospital approximately 5 hours after ingestion of an unknown amount of over-the-counter topical hair growth promoter containing 5% minoxidil foam. Vomiting and signs of lethargy were reported by the owner, and physical examination revealed tachycardia and hypotension. No treatments were performed, and the dog was transferred to a veterinary referral hospital for management of suspected minoxidil toxicosis. CLINICAL FINDINGS On arrival at the referral hospital, the dog was tachycardic (heart rate, 200 to 220 beats/min) and hypotensive (systolic arterial blood pressure, 70 mm Hg). Electrocardiography revealed a regular, narrow-complex tachycardia with no evidence of ventricular ectopy. TREATMENT AND OUTCOME Hypotension was effectively managed with a constant rate infusion of dopamine hydrochloride (12.5 μg/kg/min [5.7 μg/lb/min], IV). Once normotensive, the dog remained tachycardic and a constant rate infusion of esmolol hydrochloride (40 μg/kg/min [18.2 μg/lb/min], IV) was initiated for heart rate control. A lipid emulsion was administered IV as a potential antidote for the toxic effects of the lipophilic minoxidil, with an initial bolus of 1.5 mL/kg (0.7 mL/lb) given over 15 minutes followed by a continuous rate infusion at 0.25 mL/kg/min (0.11 mL/lb/min) for 60 minutes. While hospitalized, the dog also received maropitant citrate and ondansetron. Resolution of clinical signs was achieved with treatment, and the dog was discharged from the hospital 36 hours after admission. Four days later, the owner reported that the dog had made a full recovery and had returned to its typical behavior and activity level at home. CLINICAL RELEVANCE To the authors' knowledge, this is the first report of successful clinical management of accidental minoxidil toxicosis in a dog.

Central chorioretinopathy associated with topical use of minoxidil 2% for treatment of baldness

PURPOSE

Minoxidil is one of the drugs approved for the treatment of androgenetic alopecia. This article presents a case of central serous chorioretinopathy after application of topical minoxidil solution.

METHODS

We examined a 37-year-old man who complained of a positive relative scotoma, metamorphopsia and impaired dark adaptation involving the right eye. The patient reported an 8 month history of daily topical use but denied previous treatment with other drugs. Dilated fundus examination of right eye revealed central swelling located over the macula. Optical coherence tomography showed the presence of subretinal fluid. Fluorescein angiography disclosed one focal hyperfluorescent spot in the foveal area with minimal pigmentary changes limitated to that area. The patient was diagnosed with central serous chorioretinopathy (CSC) potentially related to an 8 month topical minoxidil solution administration. One month after the drug was discontinued, normal findings were found upon reexamination. The patient reported no previous episode of CSC.

CONCLUSION

Major systemic side effects from topical solution of minoxidil are rare. To our knowledge, this is the first reported case of a central serous chorioretinopathy associated with long-term use of this drug.