Canine Ehrlichiosis – ZOONOTIC 

            Ehrlichiosis is caused by the bacteria Ehrlichia canis. It is transmitted by tick bites, and enters white blood cells and destroys platelets. There are acute, subclinical and chronic phases, and the characteristic signs of infection are decreased platelet number and decreased serum proteins. Other signs include enlarged lymph nodes, liver, and spleen, joint pain, bruises, and can eventually result in neurologic problems and death. Most importantly, infected dogs have bleeding tendencies, so dogs with ehrlichiosis should not undergo surgery.  Ehrlichiosis can be diagnosed using an ELISA snap test. Also, the bacteria are visible inside cells on blood smear during the first few days of the acute phase infection. In all but the most severe cases, ehrlichiosis can be treated with antibiotics (doxycycline (5-10 mg/kg, PO or IV, sid for 10-21 days) or tetracycline (22 mg/kg, PO, tid for 2+ weeks)). Ehrlichiosis is zoonotic but can’t be obtained directly from the dog, only from a tick. Effective tick control will help prevent the disease.



            Lacerations can be the result of a variety of traumas; in Nicaragua some of the most common are machete cuts and saddle sores. The severity of the laceration also varies depending on its cause. Important steps in managing lacerations include determining the structures involved and controlling hemorrhage and infection. Sometimes surgical repair is necessary, other times they can simply be closed, though all lacerations should be thoroughly cleaned before closure. Lacerations (in horses) can result in lameness, pneumothorax, or penetration into the abdominal cavity. Saddle sores can vary from simple inflammation of the skin to necrotic and abscessed tissue. Chronic sores can turn into deep folliculitis with fibrosis and proliferative dermatitis. Sores are treated by resting the affected area, and astringent packs (which cause the skin to shrink) can be applied if available. If necessary, abscesses should be drained, necrotic tissue removed, and antibiotics given. Lacerations and saddle sores can be completely prevented by proper care of the animals.



Heartworm is a parasitic roundworm that is spread through mosquitoes that affects dogs and cats. After the mosquito bites, the worm remains under the skin to further mature, migrates to the muscles of the chest and abdomen, then enters the bloodstream where it is carried to the heart. Once in the heart, the worms enlarge, potentially completely filling the atria and ventricles, and reproduce. The microfilariae (young heartworms) travel in the bloodstream until a mosquito sucks them up when obtaining a blood sample.

Heartworms do not cause any clinical signs until they enter the heart (about 7 months postinfection). Once there, they can cause exercise intolerance, and if severe enough, weight loss, fainting, coughing up blood, and congestive heart failure. Heartworm is most commonly diagnosed using a blood sample and a heartworm snap test. Heartworms are treated with two IM injections of melarsomine dihydrochloride (Immiticide), given 24 hours apart, with the dose varying depending on severity. If the worm burden is high, treatment can result in thromboembolisms, so treatment should be spread over a period of one month. Heartworm in cats is not treatable.


Transmissible venereal tumor (TVT)

TVT is a tumor full of histiocytes that afflicts dogs. It mainly affects the external genitalia, but can also be seen on skin, oral, nasal, and other mucosal surfaces. TVT is transmitted by direct contact (the tumor cells themselves are infectious), so copulation is the most common way of transmission. The tumors can have a variety of appearances, from pedunculated to nodular to multilobulated, but they are often friable and ulcerate, inflame, and bleed easily. TVT can be easily diagnosed with a cytologic exam of a fine-needle aspirate or histologic biopsy because they consist of homogenous populations of large, round cells with distinctive centrally-located nucleoli (see picture below). Grossly, genital tumors are fairly characteristic of TVT, though other types of tumors can be confused for TVT. Initially the tumors grow rapidly for four to six months, then they typically enter a stable phase, and finally a regression phase. So spontaneous regression of the tumors can occur, though surgical excision, radiation, and chemotherapy are alternatives (but not in Nicaragua)


Babesiosis – ZOONOTIC

Babesia is a protozoan blood parasite causing hemolytic diseases, most commonly transmitted to dogs and livestock via ticks. There are three forms of the disease, peracute, acute, and chronic. Symptoms are generally similar, but with varying levels of severity, with the peracute being the most severe. Symptoms include fever, increased respiratory rate, weight loss, weakness, muscle tremors, anemia, jaundice from degraded erythrocytes, and red urine. Constipation or diarrhea may be present. The acute form demonstrates mild to moderate symptoms, while the chronic subset results in “tired” animals. In Nicaragua, blood smears will be available for diagnosis. If available, treatment can include Diminazene IM at 3-5 mg/kg, or imidocarb given SC at 1.2 mg/kg. At a dosage of 3.0 mg/kg, imidocarb provides protection from babesiosis for ~4 wk and will also eliminate B bovis and B bigemina from carrier animals.


Trypanosoma cruzi (Chagas’ Disease) – ZOONOTIC

            This is a parasitic disease transmitted by blood-sucking insects. In dogs, it often leads to symptoms include weakness, labored breathing, and generalized edema. Treatment of this disease is important since it is zoonotic. Signs of acute infection include swelling at the site of infection, tiredness, fever, enlarged spleen or liver, swollen lymph nodes, loss of appetite, +/- rash, diarrhea, and vomiting. Chronic infection can lead to irreversible heart and intestinal damage, enlarged heart, altered heart rhythms, heart failure, cardiac arrest, and enlarged parts of the digestive system, interfering with digestive function. Treatment: benznidazole


Anaplasmosis – ZOONOTIC

Anaplasmosis is a bacterial disease affecting ruminants. It is transmitted by ticks, and the bacteria live in and destroy red blood cells. Animals infected with anaplasma early in life usually have mild symptoms and retain immunity for the rest of their lives, though the disease can resurface in immunosupressed cattle. Older cattle with no previous exposure that become infected have severe symptoms, characterized by progressive anemia and all the fun things that come with anemia. Notably, pregnant infected cows may abort. Resistance to the disease differs with cattle species and breed, with Braham cattle being one of the most resistant. Anaplasmosis is diagnosed with blood smears, though a Giemsa stain is required to make a definitive diagnosis. Tetracycline antibiotics and imidocarb are used to treat it, and only one dose is needed to stop the acute disease (more are needed to eliminate carrier status). Outside the US, vaccination with the less-infectious bacteria Anaplasma centrale gives immunity to most strains of Anaplasma (live vaccines can’t be used in the US). 


Giardiosis (Giardia lamblia) – ZOONOTIC

            Giardiosis is a protozoal infection of the intestines that occurs commonly in dogs and cats, sometimes in ruminants, and rarely in horses. The protozoa live in the mucosal surfaces of the small intestines. The protozoa pass in the feces, so transmission of the disease is fecal-oral. The clinical signs of giardiosis can range from subclinical to weight loss, chronic diarrhea, and steatorrhea (fat in feces). Diagnosis can be made using fecal flotations with zinc sulfate. Giardia cysts are secreted intermittently, so multiple samples may need to be examined before completely ruling out the possibility of giardia. An ELIZA test also recently came on the market. Fenbendazole will remove cysts from the feces.



Roundworms, tapeworms, hookworms – ZOONOTIC (many)

These are all types of parasites that infect the intestinal tract of various animals.

Roundworms infect all animals. Modes of transmission are fecal/oral, transmammary, transplacental, and through a paratenic host. The main infection occurs in the intestines, but they can live latently in other tissues. Signs of infection include lack of growth, loss of condition, potbelly, and worms in the vomit and feces.

Tapeworms infect the intestinal tract of basically every species. Transmission is usually fecal-oral or by ingesting cysts in the environment (by eating grass, etc), though through fleas is another possibility. Cats can get it by eating an infected mouse (paratenic host). Infection is usually subclinical, any signs that do occur are gastrointestinal disturbances (diarrhea, unthriftiness, strong appetite). Severe cases may cause intussuceptions, seizures, and emaciation.

Hookworms infect the intestinal tract of most domestic species. Transmission is by ingestion of the larvae from the environment; some species of hookworm can be passed via colostrum or milk, transdermal, and by ingestion. The most significant clinical finding is anemia, which can be fatal in young animals.

When worm larvae are first ingested, they travel to the lungs, where they are coughed up and swallowed. They then hatch and inhabit the intestines. Damage can be done to the lungs, liver, etc. during this migrational phase.

  Diagnosis of all these worms is made via fecal analysis (flotations, smears)

Treatment for all the above worms is by “dewormers” such as dicholovos, fenbendazole, mebendazole, etc.


Large animal trichostrongyles, strongyles, roundworms

  Trichostrongyles are stomach worms that infect horses and ruminants. Once the larvae are ingested, they hatch in the stomach/abomasums. Larave live in the gastric glands (causing hyperplasia) while adults live in the lumen. Infection results in a less acidic stomach environment, protein loss, and impaired digestion, so watery diarrhea, weight loss, , edema (abdominal and bottle jaw – edema of lower jaw) and anorexia can occur.

  Strongyles are worms that live in the large intestine of horses. Transmission is by ingestion of the larvae in the environment. Strongyles ingest the mucosal plugs in the intestines, leading to hemorrhage and anemia in the host. S. vulgaris damages the cranial mesenteric artery and its branches directly, leading to hemorrhage into the intestines and thomboembolism, leading to colic, intussuception, rupture, or any other number of bad things.

  Roundworms also infect the intestinal tract. They are transmitted by ingestion of the larvae in the environment. They cause diarrhea, colic, etc. and can cause intestinal blockage or rupture.

  When worm larvae are first ingested, they travel to the lungs, where they are coughed up and swallowed. They then hatch and inhabit the intestines. Damage can be done to the lungs, liver, etc. during this migrational phase.

  Diagnosis is made by identifying the eggs in the feces. Treatment and prevention consist of antihelmintic medications (ivermectin, fenbendazole).


Sarcoptes scabei (Scabies) – zoonotic 

Scabies is a skin disease caused by mites (Sarcoptes scabei) and can affect dogs, cats, and cattle. The mite burrows into the skin and lays eggs. When the eggs hatch, the larvae crawl around on the skin. Scabies is transmissible through direct contact or by fomites (any inanimate object that can carry an infectious organism). It is highly contagious. Signs include intense pruritis (itching), thickened skin, crusty papules.

  Diagnosis is made by taking skin scrapings or a skin biopsy and then identifying the mites under a microscope. Treatment consists of topical administration of acaricides (ivermectin, doramectin, etc).


Demodex (Demodectic Mange) – zoonotic

            Demodex is a tiny mite that causes a skin disease. These mites live in the hair follicles of any/all mammals. Transmission occurs through prolonged direct contact, such as when a pup is suckling its mother.  Demodectic infection is usually subclinical. If signs develop, they consist of either dry alopecia (hair loss) and thickened skin (squamous type) or red pustules, abscesses, ulcerations, and wrinkled skin (pustular type).

            Diagnosis is made by taking deep skin scrapings and inspecting them microscopically for the presence of the mites. Recovery is usually spontaneous, so it’s usually not treated. This probably doesn't occur in Nicaragua because they’re so sick, so topical treatment with acaricides is probably suggested.


Ectoparasites - fleas, ticks, yeast 

Ectoparasites are parasites that live outside the body.

  Fleas live on the skin of their host, where they lay eggs and take blood meals. The eggs fall off the host, where they hatch into larvae that survive of the adults feces until they build a cocoon and mature into an adult, and then find their own to infect.

Clinical signs are typically only scratching. However, some animals have allergies, which results in dermatitis and pruritis.

  Ticks live on the skin of their host.

  Diagnosis is made by visually observing the parasite on the host. Treatment is with insecticides such as fipronil, imidacloprid, lufenuron.

Although the ectoparasites themselves may not cause much pathology, they often act as vectors to transmit other diseases, such as the ones previously discussed.

  Yeast is a fungal, opportunistic pathogen. It is normally found on the mucosal surfaces of animals, but can cause diseases in immunosuppressed or sick animals.

Signs: Cutaneous lesions are usually white, scabby masses

  Diagnosis is made by taking skin scrapings and microscopic surveillance. Treatment is Nystatin ointment or topical application of amphotericin B or 1% iodine solution.


Canine Distemper

Because the animals of Ometépe are not vaccinated, the occasional suspected case of canine distemper is seen. This disease first presents with a 1-3 day fever with concurrent suppression of white blood cells. Thick, cloudy ocular-nasal discharge, depression, loss of appetite, and diarrhea are common. Some dogs develop thickened skin on the pads and nose. If the animal survives the inital disease course, nervous system symptoms may develop. These symptoms run from localized twitching in a muscle group to weakness/paralysis to convulsions/seizures. They may last from 10 days up to several weeks or months. Neurological symptoms may disappear and then return.

Treatment generally includes antibiotics for secondary bacterial infections, fluids for dehydration, and anticonvulsants and sedatives for nervous manifestations. Many animals will not respond or recover.


Leptospriosis – ZOONOTIC

            The most common transmission of this disease is infected urine contacting mucous membranes, often occurring via contaminated water. The pathogen, Leptospira, localizes in the kidneys and can be shed in urine for months or years. In severe causes, there is sudden onset of weakness, anorexia, vomiting, fever, and mild eye infection. After a few days, the temperature drops and the animal becomes depressed with difficulty breathing and severe thirst. Jaundice may appear as a first symptom or later. Abdominal pain, bloody urine, and urine casts result form kidney infection. Bloody vomiting and diarrhea are common. Chronic kidney disease and infection can result. Mortality is rarely over 10%.

Treatment is with penicillin for symptomatic patients, and tetracycline derivatives or fluorouquinolones for carriers, although diagnosis is likely limited in Nicaragua. Additional treatments are symptomatic (fluids for dehydration, etc.)