Diseases of the Integumentary System

Chapter 53 Diseases of the Integumentary System


Reporting of skin diseases in horses is quite common. It is not unusual for the owner to notice various lesions as the horse is being groomed and prepared for work. Following are important questions in the history of a horse presented for skin problems:


• How old is the horse?

• What season of the year is it?

• Is the horse in a stable or on pasture?

• Is the horse maintained in a herd, or singly?

• Are other horses showing signs of skin disease?

• Where is the horse located?

Answers to these questions can help narrow down the list of potential diseases that may be affecting the animal.



INSECT HYPERSENSITIVITY


Insect hypersensitivity is a systemic, allergic reaction to the bite of an insect. The condition is usually seen during the summer months and is first noticed in animals 4 years of age or younger. The most common insects to cause the condition are those of the genus Culicoides, also known as biting gnats (Fig. 53-1).


image

Figure 53-1 Culicoides gnat.


(From Bowman DD: Georgi’s parasitology for veterinarians, ed 8, St Louis, 2003, Saunders, by permission.)




CLINICAL SIGNS



• Intense pruritus

• Alopecia, excoriation, erythema, scaling

• Urticaria (hives)

• Lesions most common along mane, ventral body


DIAGNOSIS



• Clinical signs

• Presence of the insects in the environment


TREATMENT



• Insect control, fly sprays

• Steroid therapy

• Antihistamines do not appear to be effective

• If lesions have gotten severe enough, the animal will need antibiotic therapy as well


INFORMATION FOR CLIENTS



• The occurrence and severity of insect hypersensitivity may be prevented with good management. Insect control, fly sprays, and fans may keep the gnats off the horses.

• If the animals are kept in a small paddock, manure removal may reduce the number of gnats present.


FLY BITE DERMATITIS


Lesions are seen as a result of the bite of the fly. Fly bite dermatitis is usually seen during the warmer months of the year.




CLINICAL SIGNS



• Wheals

• Pustules

• Nodules


TREATMENT



• Application of fly sprays

• Appropriate care of any wounds that may appear


LICE (PEDICULOSIS)


Lice are one of the most common ectoparasites that affect horses. Lice are host specific, and two species affect horses. Sucking lice (Haematopinus asini) are more damaging to the animal and live off its blood. Biting or chewing lice (Damalinia equi) live off the dead cells and other debris in the horse’s skin. Lice infestation is usually seen in the winter months. The reasons may be that the horse’s hair is longer and grooming may not be as thorough, and horses may congregate for warmth. Transmission of lice is through direct horse-to-horse contact, or they may be carried on inanimate objects.




CLINICAL SIGNS



• Intense pruritus, especially around mane and tail

• Can see adults or eggs in the hair


DIAGNOSIS



• Visualize the adults and eggs in the hair coat


TREATMENT



• Topical shampoos (pyrethrins and organophosphates, although organophosphates should be avoided if possible for safety reasons) can be used.

• Treat environment.

• Clip horses.

• Must treat all horses on premises.

• Ivermectin has been used, with more effect against the sucking lice than biting lice.


MITES


Many different species of mites are normal inhabitants of the horse’s skin, and some are free living in the environment. Disease caused by mites is most often seen when an animal becomes immunocompromised.




CLINICAL SIGNS



• Intense itching

• Distribution of lesions depends on species of mite


DIAGNOSIS



• Microscopic examination of skin scrapings


TREATMENT



• Lime sulfur dips

• Pyrethrin dips

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  3. Diseases of the Cardiovascular System
  4. Hematologic Diseases

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Aug 31, 2016 | Posted by in GENERAL | Comments Off on Diseases of the Integumentary System

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