A 6-year-old male neutered Alaskan malamute mixed breed dog is presented with a history of minimal hair regrowth and abnormally coarse coat texture 6 months after grooming.
Rebecca Mount, DVM, DACVD
Dermatology for Animals, Albuquerque, New Mexico
December 2024
History
Loki has a 2-year history of atopic dermatitis which is well controlled with daily oclacitinib and historical immune mediated thrombocytosis which has been in remission without therapy for about 1 year. At his annual recheck exam, the owner reported that due to matting issues they had Loki shaved by a groomer about 6 months prior, but had seen minimal hair regrowth on the trunk and that the coat texture was coarser than normal. The patient was minimally pruritic. The current diet was an over-the-counter commercial kibble and numerous treats. The dog was not on any other additional medications or supplements.
Exam
On physical exam there was patchy alopecia intermixed with some hair regrowth on the trunk. The new hair along midline was normal coat texture and color, but the hair growth on the lateral thighs and flanks was coarser than normal. Alopecia extended down the limbs with patchy regrowth, but the hair coat on the head and tail which were not shaved was normal. There was minimal erythema and mild scaling noted on the dorsum and flanks. Otoscopic exam showed mild erythema with scant debris.
Figure 1:
Diagnostics
To evaluate for hormonal causes of hair cycle arrest a full blood panel including: a complete blood count, chemistry panel, and thyroid panel (T4, free T4, and TSH) was performed and all values including thyroid values were within normal range.
The history and owner discussion ruled out any possible exposure to topical steroids or transdermal hormone replacement creams. Additionally, there were no clinical signs (polyuria/polydipsia/polyphagia, panting, weight gain, etc.) supportive hyperadrenocorticism.
Assessment
Post Clipping Alopecia (Hair Cycle Arrest)
Treatment Plan
Unfortunately, there are no specific treatments for post clipping alopecia and regrowth generally occurs slowly over time.
Melatonin is synthesized by the pineal gland and has a role in the control of photoperiod- dependent hair changes. Increased daily secretion is noted with shorter days and decreased daylight. Melatonin is thought to have a role in the seasonal growth and shedding in dogs. Melatonin has been used in various hair cycle disorders including: recurrent flank alopecia, Alopecia X, and other sex hormone alopecia. Melatonin has been used orally or in implants with varying response. Oral doses can range from 0.5-1.3mg/kg every 12 hours . Melatonin is generally well tolerated and was used in this case at 10mg every 12 hours to see if we could increase the rate of hair regrowth.
Follow-up
At the 4 week follow up minimal hair regrowth was noted by the owner. Three months later more hair growth was noted on the trunk and limbs, but the texture was still coarser than the normal hair coat. At the 6-month follow-up hair regrowth was improved but still incomplete. At the 6-month mark, melatonin was discontinued as it did not appear to be having any marked effect on the hair regrowth.
Discussion
Post clipping alopecia is an anecdotal condition that occurs when there is delayed or failed hair regrowth following clipping of the hair. This condition has been seen focally at sites shaved for medical procedures, catheter placement or surgical preparation, or with grooming. Post clipping alopecia should be considered in cases in which hair regrowth has not occurred within 3 months of shaving. Although the exact mechanism is unclear, it is thought to be a form of hair cycle arrest due to delayed anagen.
Plush or long coated breeds including: Alaskan malamutes, American Eskimo, chow chow, Pomeranians, Samoyed, and Siberian husky appear to be more at risk for developing post clipping alopecia. Other causes of hair cycle arrest, such as hypothyroidism and Cushing’s disease, should be ruled out. Additionally, in younger dogs, a follicular dysplasia should be considered and ruled out.
Overall, the prognosis for post clipping alopecia (hair cycle arrest) is good as the changes are predominantly cosmetic. Hair regrowth can take up 24 months. Additionally, the hair coat may be a different color or texture than the normal coat. Due to the prolonged time expected for hair regrowth it is important to discuss the timeline with owners.
References
- Scott, D.W., Miller Jr, W.H., & Griffin, C.E. (2013). Muller and Kirk’s Small Animal Dermatology (7th). Elsevier, pg. 154-155 and 564-566.