Notoedres spp

From Cat

Notoedric mange, caused by Notoedres cati, is a fairly common parasitic skin disease of cats characterised by scabby, scaly facial disease known as head mange.

Notoedres mites are closely related to Sarcoptic mange mites of dogs and thus the two infections have some similarity. The mite lives in the epidermis and its life cycle is similar to that of Sarcoptes scabiei. The condition is highly contagious, especially by direct contact to cats, dogs and man (where it causes a pruritic rash)[1].

Although Notoedric mange is now rare in European countries, it is still common in Italy, Switzerland, Soain, Slovenia, Croatia and Australia, where it is either endemic or present in an epizootic state. Young animals and cats debilitated with retroviral infections (FeLV, FIV) are particularly susceptible.

Clinical signs

Both conditions typically begin with itchy crusts and scales an the ear margins. Notoedric mange progresses to involve the face and ultimately, if the skin disease is ignored, it will cover the cat’s entire body. The term “scabies” is somewhat colloquial and refers to a mite infection with any of the mites in Sarcoptidae family. Signs appear initially on the face and pinnae and are characterised by alopecia, erythema, scaling and thick crusts (a notoedric 'helmet'). With time, these lesions spread to limbs, abdomen and peri-anal region. Hyperpigmentation, lichenification and excoriation are then observed. Pruritus is variable (mild to severe)[2].

Diagnosis

A scraping of the crusty skin can be examined under the microscope. Adult mites and immature stages (larvae, nymphs and eggs) are generally not difficult to detect if they are present; still, their absence does not rule Notoedric mange out. Sometimes a trial course of treatment is needed to fully rule out the infection. The presence of the mite is highly inflammatory, hence the intense itching.

A differential diagnosis of other causes of facial pruritus must be considered.

Notoedres mites are spread by touch and they can certainly infection humans, dogs, or even rabbits. They do not live off their host for more than a few days at best thus transmission is generally by direct contact with an infected individual.

Treatment

There are several options for the treatment of this condition.

Organophosphate dips – In the past a series of 6 or 7 lime sulphur baths or Amitraz (mitaban®) dips were used to control this infection. This certainly works but the cat’s general dislike of bathing had created need for a more convenient treatment. Further, lime sulphur has an extremely objectionable smell and will discolour fur. Amitraz tends to produce sedation in some patients and headaches in some humans.

Ivermectin – injectable ivermectin has become the most common treatment due to its convenience and efficacy. Treatment is typically weekly or every 2 weeks for a month and recovery is prompt[3]. Selamectin appears to have some efficacy against Notoedres spp[4]. This product appears to be most beneficial in prevention of future infections (it is meant to be used monthly on an indefinite basis for flea control) and provides a convenient means to treat other housemate cats[5]. Doramectin at 290 micrograms/kg is sufficient to control notoedric mange in cats[6]

References

  1. Euguere, E & Prelaud, P (2000) A practical guide to feline dermatology. Merial, France
  2. Foley, RH (1991) Comp Cont Educ Pract Vet 13:783-800
  3. Bigler B et al (1984) 1st successful results in the treatment of Notoedres cati with ivermectin. Schweiz Arch Tierheilkd 126(7):365-367
  4. Itoh N et al (2004) Treatment of Notoedres cati infestation in cats with selamectin. Vet Rec 154(13):409
  5. Merck Veterinary Manual
  6. Delucchi L & Castro E (2000) Use of doramectin for treatment of notoedric mange in five cats. J Am Vet Med Assoc 216(2):215-216, 193-4