Customer hello and I hope I can be of some assistance. I just signed on and saw your question and it appears that a different expert "opted out" meaning she decided not to answer the question and to open it up to a different expert. Unfortunately this can cause a delay as often it is not obvious right away to other experts that this question is still needing to be answered. Sorry for the long delay, but I hope I can be of assistance to you.
I did some research regarding your question. It sounds like your min pin's have hair loss or alopecia with really no other symptoms, both in the neck/chest region. There could be a number of causes of this. Usually in cases of hair loss it is good to first rule out parasites, fungal infections etc. Those things sound unlikely in your dog. But typically a vet may do a skin scraping to check for mites, a fungal culture, etc. If all of that comes back negative, then we start to consider alopecia disorders, of which there are many.
I researched min pin's in particular and they are prone to a few types of genetic alopecia disorders. One I might suspect in your dogs is simply called "pattern alopecia" or "pattern baldness." This is often located in exactly the area are you describe, the front of the neck. This has a genetic basis and is more common in this breed. There really is no way to prevent it as it is genetic, and there is no specific therapy. However, some cases may respond to melatonin supplements to help get the hair growing again. Here is some pharmaceutical information on melatonin from a veterinary handbook:
Oral and implantable pineal gland hormone
Potential uses include: alopecia in dogs, sleep and behavior disorders in cats and dogs, adjust seasonally controlled fertility in sheep, goats, and horses, and adjunctive treatment for adrenal disease in ferrets
Adverse effects appear to be minimal, but little experience
Potential contraindications include: pregnancy, sexually immature animals, and liver dysfunction
A naturally occurring hormone produced in the pineal gland, melatonin occurs as a pale yellow, crystalline solid and has a molecular weight of 232. It can be derived from natural sources or by synthetic means.
Unless otherwise labeled store at room temperature in tight containers.
Melatonin is involved with the neuroendocrine control of photoperiod dependent molting, hair growth and pelage color. Melatonin stimulates winter coat growth and spring shedding occurs when melatonin decreases. The mechanism of how melatonin induces these effects is not well understood. It may have direct effects on the hair follicle or alter the secretion of prolactin and/or melanocyte stimulating hormone.
Melatonin also increases serum prolactin levels, growth hormone, and increases response to growth hormone releasing hormone. Long-term use may decrease luteinizing hormone. Melatonin is also ostensibly a free radical scavenger.
Melatonin may be useful to treat Alopecia-X in Nordic breeds, Canine pattern baldness, or canine recurrent flank alopecia in dogs. It has also has been used anecdotally for the treatment of sleep cycle disorders in cats and geriatric dogs and to treat phobias and separation anxiety in dogs. Melatonin implants are used in the mink and fox pelt industries to promote the development of luxurious hair coats. Implants are also used to improve early breeding and ovulation rates in sheep and goats. Preliminary research is being done for this purpose in horses also.
In pigs, one study (Bubenik, Ayles et al. 1998) demonstrated that 5 mg/kg in feed reduced the incidence of gastric ulcers in young pigs.
No specific information was located.
Melatonin implants are considered contraindicated in pregnant or sexually immature animals. There are very specific times for administration depending on latitude, hemisphere, and breed. Animals that are nursing young may not benefit from implant therapy.
In humans, melatonin is considered contraindicated in patients with hepatic insufficiency as it is cleared hepatically. It is also contraindicated in patients with a history of cerebrovascular disease, depression or neurological disorders. Use caution in patients with renal impairment.
No information located; use with caution.
Melatonin appears to be quite safe in dogs. Side effects in dogs when given orally are rare, although sex hormone secretion and fertility may be affected. Subcutaneous implants in dogs have been associated with sterile abscesses.
Adverse effects reported in humans include altered sleep patterns, hypothermia, sedation, tachycardia, confusion, headache and pruritus.
Little information available; unlikely to cause significant morbidity after a single overdose.
Melatonin may potentiate the effects of benzodiazepines or succinylcholine.
For dermatologic conditions:
1. For experimental treatment of Alopecia-X in Nordic breeds, Canine pattern baldness, or canine recurrent flank alopecia: Empirical dose of one to four 12 mg implants SC. Retreatment may be necessary once or twice a year. If implants are unavailable, oral melatonin at 3-6 mg every 8-12 hours may be tried. Although appears to be safe, recommend having owners sign a release form noting the "experimental" nature of treatment. (Paradis 2000)
2. For treatment of canine recurrent flank alopecia or seasonal flank alopecia: 2-3 mg per dog PO once daily for 3-5 days weekly or monthly or this as a daily dose. Doses of up to 10 mg per dog have used. Improvement is usually seen in one month with maximal improvement in 3 months. (Merchant 2000)
3. For treatment of Alopecia-X in Nordic breeds, Canine pattern baldness, or canine recurrent flank alopecia: 3 mg for dogs under 10 kg and 6 mg for dogs 10 kg or greater PO q8-12 hrs for 6 to 8 weeks. (Campbell 1999)
For sleep disorders (nocturnal activity):
1. 3-6 mg (total dose) PO q12-24h (Virga 2002)
For sleep disorders (nocturnal activity):
1. 3-12 mg (total dose) PO q12-24h (Virga 2002)
For adjunctive treatment of adrenal disease:
1. Anecdotal reports of using melatonin 1 mg PO once daily 8-9 hours after sunrise or using the injectable mink implant approximately once every 4 months have been received. Monitor ongoing reports for further information.
1) Clinical efficacy
For use in small animals, must be administered as directed to be effective. Relatively "experimental"; safety and efficacy are not clearly established.
Dosage Forms/Approval Status/Withholding Times
An 18 mg implant for sustained subcutaneous release is available in a variety of countries. One trade name is Regulin®. It is labeled for use in sheep (UK and NZ) and goats (NZ) to improve early breeding and ovulation rates.
There reportedly are mink implants available in the United States from Neo-Dynamics(NNN) NNN-NNNN and a 5.4 mg implant product marketed for ferrets (Ferretonin®; Melatek, LLC; www.melatek.net). Actual approval status is not known.
Melatonin tablets are available in a variety of strengths from a variety of sources. Common strengths available range from 0.5 mg to 3 mg tablets. Sustained release capsules (3 mg) and oral liquid (500 mcg/ml) may also be available. Because melatonin is considered a "nutrient" there is no official labeling or central quality control systems for it in the USA. Purchase from reputable sources.
Ideally I would recommend a visit to your local vet to have these areas examined, skin scraping, etc. if you haven't already done so. But if you are interested in trying the melatonin, it appears to be considered very safe in dogs, but it has not been extensively studied in dogs. I would check with your vet before using it however, to be sure your pets don't have any reasons (previous medical problems or other medications) they should not take this. It can take a number of weeks to see a response. I hope this information is helpful to you and again, I am sorry you experienced a long delay in getting an answer. My best to you and your min pins! Dr. Marcia