Diagnosis of Hemic-Lymphatic Diseases by Presenting Sign

Bleeding Disorders

Indications of bleeding disorders include petechial or ecchy- motic hemorrhages of mucous membranes, prolonged bleeding from venipuncture sites or surgical wounds, pas­sage of blood from body orifices, or development of subcuta­neous or periarticular swellings.

Inherited afibrinogenemia has been reported in a family of Saanen goats (Breukink et al. 1972). The inheritance pattern is incomplete autosomal dominant. There is com­plete absence of circulating fibrinogen in homozygous individuals, and goats thus affected do not live past the kid stage. Unchecked umbilical hemorrhage at birth is the most common presentation, but recurrent hemarthroses and subcutaneous and mucosal hemorrhage can also be seen. Clotting time, thrombin time, stage 1 prothrombin, and partial thromboplastin times are all prolonged in afi­brinogenemia. Fibrinogen concentration, as measured by bioassay of thrombin clottable protein, is always under 0.15 g/dL and is usually 0. Acquired coagulation disorders presumably occur in the goat at a rate similar to other spe­cies, but the literature on specific causes or cases of coagu­lopathy in the goat is sparse. Evidence of bleeding from the orifices of a dead goat is suggestive of anthrax.

Thrombocytopenia is reported as a consistent finding in African trypanosomosis in all affected species, including goats (Davis 1982). The degree of thrombocytopenia and the development of subsequent hemorrhage are directly correlated to the degree of parasitemia that develops.

Bracken fern (Pteridium aquilinum) ingestion by cattle can lead to a syndrome of pancytopenia with leukopenia, thrombocytopenia, and anemia. Melena, epistaxis, and widespread petechial and ecchymotic hemorrhage are major clinical findings.

Hemorrhagic diathesis is considered to be a clinical man­ifestation of severe, diffuse liver disease in other farm ani­mal species (Constable et al. 2017). However, a review of liver diseases of sheep and goats did not identify coagulopa­thy as a clinical outcome of hepatic disease (Fetcher 1983). The only report documenting decreased clotting activity in goats in association with liver disease involved experimen­tal dosing with carbon tetrachloride (Jones and Shah 1982).

Anemia

Anemia is suggested clinically by pale or white mucous membranes (Figure 7.1), exercise intolerance, tachypnea, tachycardia, possible systolic murmurs, weakness, and (in extreme cases) collapse. When anemia is a result of

Figure 7.1 White-colored conjunctiva characteristic of a goat with marked anemia. In normal goats, the color is pink to red. Source: Courtesy of Dr. M.C. Smith.

intravascular hemolysis, then jaundice and hemoglobinu­ria are also important clinical signs. Signs of anemia are frequently accompanied by signs of hypoproteinemia, par­ticularly intermandibular edema, ascites, and weight loss. Anemia is a common and important clinical presentation in goats.

Causes of Hemolytic Anemia

Important, established causes of hemolytic anemia in goats include the hemoparasitic diseases anaplasmosis, babesiosis, eperythrozoonosis, and theileriosis; nutritional disorders including copper toxicosis, kale ingestion, and consumption of other, regional poisonous plants; and an infectious cause, leptospirosis.

Other suspected causes of hemolytic anemia in goats include infections due to Clostridium novyi type D (Cl. hemolyticum) and Clostridium perfringens type A, as reported in sheep. Experimental poisoning with oak tan­nins caused marked hemolytic anemia in goats, but natu­rally occurring oak poisoning is uncommon in this species (Begovic et al. 1978). Experimental infections of sarco- cystosis (sarcosporidiosis) produce hemolytic anemia (Dubey et al. 1981), but almost all known naturally occur­ring infections in goats are subclinical, producing muscle cysts seen at slaughter or necropsy, as discussed further in Chapter 4.

Two reports suggest hypophosphatemia as the cause of hemolytic anemia and hemoglobinuria in female goats, but in two of the three reported cases, serum inorganic phosphorus levels were in the normal range (Setty and Narayana 1975; Samad and Ali 1984). In cattle with post­parturient hemoglobinuria, serum inorganic phosphorus levels are well below the normal range.

Causes of Blood Loss Anemia

Anemia due to loss of blood is of major clinical significance in goats. The condition is most often associated with some form of parasitism. Important causes of blood loss anemia include infestations by Haemonchus spp. and liver flukes, especially Fasciola hepatica. External parasitic causes include sucking lice, ticks, and fleas (Schillhorn van Veen and Mohammed 1975). Predation may be another impor­tant cause of blood loss. While wild predators can be expected to kill goats outright unless interrupted, domesti­cated dogs often maim goats without killing them. Severe hemorrhagic trauma often results.

Causes of Anemia Due to Impaired Erythropoiesis

Anemias of this type occur infrequently or are overshad­owed by other concurrent and more prominent clinical signs. Nutritional causes include cobalt, copper, and iron deficiencies. Toxic causes include fluorosis and possibly bracken fern ingestion. Anemia of chronic infection also occurs in goats (e.g., in paratuberculosis).

Iron deficiency is associated with prolonged feeding of doe's milk to kids without mineral supplementation or access to forage. Copper deficiency manifests primarily as a neurologic disease in young kids. In experimentally induced cobalt deficiency in goats, a macrocytic, normo­chromic anemia was observed in addition to weight loss (Mgongo et al. 1981). In naturally occurring cases of cobalt deficiency, ill-thrift is a consistent finding, but the pres­ence of anemia is variable (Brain 1983; Black et al. 1988). Non-regenerative anemia has been documented in chronic fluorosis of goats grazing near a superphosphate factory in Egypt (Karram et al. 1984). One incident of bracken fern poisoning has been reported in goats. Anemia was present, but may have been due to concurrent parasitism (Tomlinson 1983).

There is one report of myelofibrosis occurring in 11 pygmy goat kids from two litters with a breeding history that suggested that the condition was inherited. Affected kids were lethargic, had poor appetite, pale mucous mem­branes, and died by 12 weeks of age. Hematologic examina­tion revealed severe anemia, moderate leukopenia, severe neutropenia, and reticulocytosis. At necropsy, marked myelofibrosis was noted, especially in diaphyseal bone marrow samples, and there was evidence of active extramedullary hematopoiesis at multiple sites, including thymus gland, tonsils, lymph nodes, liver, and elsewhere (Cain et al. 1994).

Documented causes of anemia in goats are summarized in Table 7.6. The table emphasizes concurrent clinical and laboratory findings, such as hypoproteinemia and hemo­globinuria, which can aid in the differential diagnosis of anemia. All the hemoparasitic diseases, leptospirosis, cop­per poisoning, phosphorus deficiency, kale ingestion, and other poisonous plants causing anemia, are discussed in detail later in this chapter. Other diseases associated with anemia are discussed elsewhere in the text because other clinical signs predominate.

Lymphadenopathy

Transient swelling of select regional lymph nodes can be expected in common, localized infections such as mastitis, or subsequent to vaccinations.

Table 7.6 Anemia in goats: aids for differential diagnosis.